allow to specify EXTERNAL_LIBCLANG_PATH
script detects Andorid's libclang not system's. this make it to work correctly.
Revert "Revert "Only removing our signs in buffer, no all""

This reverts commit 9d06a3e54cdfa35033434c0127e75d127ad562b6.

Conflicts:
	python/ycm/vimsupport.py
Merge branch 'master' of https://github.com/tex/YouCompleteMe