YCM works correctly when 'out' directory is a symlink (continued).

It used to work after my previous fix 37accc2cd, but then it broke again.
This CL changes the way how "-I" arguments are transformed.

BUG=NONE
TEST=manually
NOTRY=true

Review URL: https://codereview.chromium.org/528293002

Cr-Original-Commit-Position: refs/heads/master@{#293519}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 95e4bfd7a9fd1333343a5a6bfc7c6ef03cbe10ce
1 file changed