vcom and vlog create files in current directory on disk

## Information

**VIM version**

VIM - Vi IMproved 8.1 (2018 May 18, compiled Jun 18 2019 12:07:09)
Included patches: 1-1565

Operating System: RHEL 6.9 64b

## What went wrong

The 'vlog' and 'vcom' Questa/Modelsim linters create a directory called 'work' with a handful of library files inside the current working directory as a byproduct of linting with ALE. These files pollute the cwd and are unnecessary. They can be avoided by modifying the call to vlog/vcom

## Reproducing the bug

0. Ensure questa/modelsim is installed and on PATH
1. Open a VHDL file with the vcom linter enabled or open a Verilog file with the vlog linter enabled.
2. Close vim
3. Observe that there is a new directory called 'work' in the cwd with compiled library files resident.

## Fixing the bug
I worked around the bug by using the -work option with a Tempname for both vlog and vcom. -work lets you specify a library path rather than the default of ./work. The temp file will then get cleaned up automatically when vim exits.

Before (vlog)
```viml
function! ale_linters#verilog#vlog#GetCommand(buffer) abort
return '%e ' . ale#Pad(ale#Var(a:buffer, 'verilog_vlog_options')) . ' %t'
endfunction
```
After
```viml
function! ale_linters#verilog#vlog#GetCommand(buffer) abort
let l:tmpdir = ale#util#Tempname()

return '%e ' . ale#Pad(ale#Var(a:buffer, 'verilog_vlog_options')) . ' -work ' . l:tmpdir . ' %t'
endfunction
```
Before (vcom)
```viml
function! ale_linters#vhdl#vcom#GetCommand(buffer) abort
return '%e ' . ale#Pad(ale#Var(a:buffer, 'vhdl_vcom_options')) . ' %t'
endfunction
```
After
```viml
function! ale_linters#vhdl#vcom#GetCommand(buffer) abort
let l:tmpdir = ale#util#Tempname()

return '%e ' . ale#Pad(ale#Var(a:buffer, 'vhdl_vcom_options')) . ' -work '. l:tmpdir . ' %t'
endfunction
```

### :ALEInfo

ALEInfo output for an empty Verilog file:
Current Filetype: verilog_systemverilog
Available Linters: ['iverilog', 'verilator', 'vlog', 'xvlog']
Enabled Linters: ['vlog']
Suggested Fixers:
'remove_trailing_lines' - Remove all blank lines at the end of a file.
'trim_whitespace' - Remove all trailing whitespace characters at the end of every line.
Linter Variables:

Global Variables:

let g:ale_cache_executable_check_failures = v:null
let g:ale_change_sign_column_color = 0
let g:ale_command_wrapper = ''
let g:ale_completion_delay = v:null
let g:ale_completion_enabled = 0
let g:ale_completion_max_suggestions = v:null
let g:ale_echo_cursor = 1
let g:ale_echo_msg_error_str = 'Error'
let g:ale_echo_msg_format = '%code: %%s'
let g:ale_echo_msg_info_str = 'Info'
let g:ale_echo_msg_warning_str = 'Warning'
let g:ale_enabled = 1
let g:ale_fix_on_save = 0
let g:ale_fixers = {}
let g:ale_history_enabled = 1
let g:ale_history_log_output = 1
let g:ale_keep_list_window_open = 0
let g:ale_lint_delay = 200
let g:ale_lint_on_enter = 1
let g:ale_lint_on_filetype_changed = 1
let g:ale_lint_on_insert_leave = 1
let g:ale_lint_on_save = 1
let g:ale_lint_on_text_changed = 'normal'
let g:ale_linter_aliases = {}
let g:ale_linters = {'vhdl': ['vcom'], 'verilog_systemverilog': ['vlog']}
let g:ale_linters_explicit = 0
let g:ale_list_vertical = 0
let g:ale_list_window_size = 10
let g:ale_loclist_msg_format = '%code: %%s'
let g:ale_lsp_root = {}
let g:ale_max_buffer_history_size = 20
let g:ale_max_signs = -1
let g:ale_maximum_file_size = v:null
let g:ale_open_list = 0
let g:ale_pattern_options = v:null
let g:ale_pattern_options_enabled = v:null
let g:ale_set_balloons = 0
let g:ale_set_highlights = 1
let g:ale_set_loclist = 1
let g:ale_set_quickfix = 0
let g:ale_set_signs = 1
let g:ale_sign_column_always = 0
let g:ale_sign_error = '>>'
let g:ale_sign_info = '--'
let g:ale_sign_offset = 1000000
let g:ale_sign_style_error = '>>'
let g:ale_sign_style_warning = '--'
let g:ale_sign_warning = '--'
let g:ale_sign_highlight_linenrs = 0
let g:ale_statusline_format = v:null
let g:ale_type_map = {}
let g:ale_use_global_executables = v:null
let g:ale_virtualtext_cursor = 0
let g:ale_warn_about_trailing_blank_lines = 1
let g:ale_warn_about_trailing_whitespace = 1
Command History:

(executable check - success) vlog
(finished - exit code 0) ['/bin/bash', '-c', '''vlog'' -quiet -lint ''/tmp/vrylSVN/0/test.v''']

<<>>

ALEInfo output for an empty VHDL file
Current Filetype: vhdl
Available Linters: ['ghdl', 'vcom', 'xvhdl']
Enabled Linters: ['vcom']
Suggested Fixers:
'remove_trailing_lines' - Remove all blank lines at the end of a file.
'trim_whitespace' - Remove all trailing whitespace characters at the end of every line.
Linter Variables:

let g:ale_vhdl_vcom_executable = 'vcom'
let g:ale_vhdl_vcom_options = '-2008 -quiet -lint'
Global Variables:

let g:ale_cache_executable_check_failures = v:null
let g:ale_change_sign_column_color = 0
let g:ale_command_wrapper = ''
let g:ale_completion_delay = v:null
let g:ale_completion_enabled = 0
let g:ale_completion_max_suggestions = v:null
let g:ale_echo_cursor = 1
let g:ale_echo_msg_error_str = 'Error'
let g:ale_echo_msg_format = '%code: %%s'
let g:ale_echo_msg_info_str = 'Info'
let g:ale_echo_msg_warning_str = 'Warning'
let g:ale_enabled = 1
let g:ale_fix_on_save = 0
let g:ale_fixers = {}
let g:ale_history_enabled = 1
let g:ale_history_log_output = 1
let g:ale_keep_list_window_open = 0
let g:ale_lint_delay = 200
let g:ale_lint_on_enter = 1
let g:ale_lint_on_filetype_changed = 1
let g:ale_lint_on_insert_leave = 1
let g:ale_lint_on_save = 1
let g:ale_lint_on_text_changed = 'normal'
let g:ale_linter_aliases = {}
let g:ale_linters = {'vhdl': ['vcom'], 'verilog_systemverilog': ['vlog']}
let g:ale_linters_explicit = 0
let g:ale_list_vertical = 0
let g:ale_list_window_size = 10
let g:ale_loclist_msg_format = '%code: %%s'
let g:ale_lsp_root = {}
let g:ale_max_buffer_history_size = 20
let g:ale_max_signs = -1
let g:ale_maximum_file_size = v:null
let g:ale_open_list = 0
let g:ale_pattern_options = v:null
let g:ale_pattern_options_enabled = v:null
let g:ale_set_balloons = 0
let g:ale_set_highlights = 1
let g:ale_set_loclist = 1
let g:ale_set_quickfix = 0
let g:ale_set_signs = 1
let g:ale_sign_column_always = 0
let g:ale_sign_error = '>>'
let g:ale_sign_info = '--'
let g:ale_sign_offset = 1000000
let g:ale_sign_style_error = '>>'
let g:ale_sign_style_warning = '--'
let g:ale_sign_warning = '--'
let g:ale_sign_highlight_linenrs = 0
let g:ale_statusline_format = v:null
let g:ale_type_map = {}
let g:ale_use_global_executables = v:null
let g:ale_virtualtext_cursor = 0
let g:ale_warn_about_trailing_blank_lines = 1
let g:ale_warn_about_trailing_whitespace = 1
Command History:

(executable check - success) vcom
(finished - exit code 2) ['/bin/bash', '-c', '''vcom'' -2008 -quiet -lint ''/tmp/vIO6HZx/0/test.vhd''']

<<>>
** Error (suppressible): /tmp/vIO6HZx/0/test.vhd(2): (vcom-1491) Empty source files.
<<>>