I most often get no useful completion - in my big project.

## Problems summary

Using deoplete / deoplete-clang, writing C++, I often get only weak completion (just a list of could-be-useful words/predictions). For example in this function, why don't I get completion on std::deque?

Another case:
The class has a member `SAP& broadphase_alg;` with several public members and methods. But again I only get useless information: 
## Expected

Proper completion.
## Environment Information
- OS: Arch Linux
- Neovim version: 0.1.4
## Provide a minimal init.vim with less than 50 lines and not plugin manager (Required!)

``` vim
" Deoplete
let g:deoplete#enable_at_startup = 1
let g:deoplete#sources#clang#libclang_path = '/usr/lib/libclang.so'
let g:deoplete#sources#clang#clang_header = '/usr/lib/clang'
let g:deoplete#sources#clang#std#cpp = 'c++11'

syntax enable
filetype plugin indent on

let $NVIM_TUI_ENABLE_CURSOR_SHAPE=1

" Files
set backup
set backupdir=~/.local/share/nvim/backup
set directory=~/.local/share/nvim/swap
set undofile
set undodir=~/.local/share/nvim/undo
" Basic configuration
set expandtab
set shiftwidth=4
set tabstop=4
set softtabstop=4
set clipboard+=unnamedplus
set showcmd
set number
set scrolloff=15
set hlsearch
set cursorline
set nocompatible
set esckeys

autocmd BufNewFile, BufRead *.c++ setfiletype cpp

```
## The reproduce ways from neovim starting (Required!)

I would have to share all the code of my project. I tried making a minimal test case but in the test case it all works... it's only in my big project deoplete-clang seldomly works.
## Generate a logfile if appropriate

http://sprunge.us/EWVG

I guess I have some things missing, but I just couldn't reproduce the errors with a minimal test case. I really hope you can help me. I've been struggling a long time to write this issue (finding any pattern in the problems, finding a minimal test case...). Please ask me if there's anything more you need to know. Maybe I've overlooked something really basic.