Read .syntastic_c_config in .ycm_extra_conf.py

[tsto]

If you use syntastic with C, you already have your CPP flags stored in a file like .syntastic_c_config. YCM should read that if it's there, to save me pasting them or some other hack.

Something like this works for me: https://gist.github.com/tsto/4718358

Note, my python is terrible.

[Valloric]

Sorry, but this does not cross my code-needed-to-write-and-test/benefit ratio. It's such a small thing.

Still, thanks for the feedback!