Completion for single C files without compile_commands.json does not work

## Information

**VIM version**

```
VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Jun 07 2022 00:51:41)
Included patches: 1-5046
```

Operating System: `Arch Linux x86_64 `

## What went wrong

Completion does not work when opening a single C source code file and compile_commands.json does not exist in the directory.

When a single C source code file is opened, basic suggestions should be offered based on the language, standard library and file definitions.

When opening the same file in vscode with the clangd extension or vim with coc.nvim and coc-clangd the completion works.

If an empty compile_commands.json is created in the directory, the ALE completion works as intended.

## Reproducing the bug

1. Create a new directory.
2. Create a new C file in that directory.
3. Open the file with Vim.
4. Type "in", the completion pop-up should open and suggest several words, including "int", but it does not.

### :ALEInfo

```
Current Filetype: c
Available Linters: ['cc', 'ccls', 'clangd', 'clangtidy', 'cppcheck', 'cpplint', 'cquery', 'cspell', 'flawfinder']
Linter Aliases:
'cc' -> ['gcc', 'clang']
Enabled Linters: ['cc', 'ccls', 'clangd', 'clangtidy', 'cppcheck', 'cpplint', 'cquery', 'cspell', 'flawfinder']
Ignored Linters: []
Suggested Fixers:
'astyle' - Fix C/C++ with astyle.
'clang-format' - Fix C/C++ and cuda files with clang-format.
'clangtidy' - Fix C/C++ and ObjectiveC files with clang-tidy.
'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.
'uncrustify' - Fix C, C++, C#, ObjectiveC, ObjectiveC++, D, Java, Pawn, and VALA files with uncrustify.
Linter Variables:

let g:ale_c_always_make = 1
let g:ale_c_build_dir = ''
let g:ale_c_build_dir_names = ['build', 'bin']
let g:ale_c_cc_executable = ''
let g:ale_c_cc_options = '-std=c11 -Wall'
let g:ale_c_ccls_executable = 'ccls'
let g:ale_c_ccls_init_options = {}
let g:ale_c_clangd_executable = 'clangd'
let g:ale_c_clangd_options = ''
let g:ale_c_clangtidy_checks = []
let g:ale_c_clangtidy_executable = 'clang-tidy'
let g:ale_c_clangtidy_extra_options = ''
let g:ale_c_clangtidy_options = ''
let g:ale_c_cppcheck_executable = 'cppcheck'
let g:ale_c_cppcheck_options = '--enable=style'
let g:ale_c_cpplint_executable = 'cpplint'
let g:ale_c_cpplint_options = ''
let g:ale_c_cquery_cache_directory = '/home/pablo/.cache/cquery'
let g:ale_c_cquery_executable = 'cquery'
let g:ale_c_flawfinder_error_severity = 6
let g:ale_c_flawfinder_executable = 'flawfinder'
let g:ale_c_flawfinder_minlevel = 1
let g:ale_c_flawfinder_options = ''
let g:ale_c_parse_compile_commands = 1
let g:ale_c_parse_makefile = 0
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 = 100
let g:ale_completion_enabled = 1
let g:ale_completion_max_suggestions = 50
let g:ale_disable_lsp = 0
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 = {}
let g:ale_linters_explicit = 0
let g:ale_linters_ignore = {}
let g:ale_list_vertical = 0
let g:ale_list_window_size = 10
let g:ale_loclist_msg_format = '%code: %%s'
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_root = {}
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) clang
(finished - exit code 0) ['/bin/zsh', '-c', '''clang'' -S -x c -o /dev/null -iquote ''/home/pablo/Documents/Proyectos/C/algorithms'' -std=c11 -Wall - < ''/tmp/vdYSEBV/1/test.c''']

<<>>

(executable check - success) clang-tidy
(finished - exit code 0) ['/bin/zsh', '-c', '''clang-tidy'' ''/home/pablo/Documents/Proyectos/C/algorithms/test.c''']

<<>>

(executable check - failure) cppcheck
(executable check - failure) cpplint
(executable check - failure) cspell
(executable check - failure) flawfinder
```