[Vim/YCM] Fix missing system headers when YCM was built with its own libclang.

Bug: 932667
Change-Id: I2eb9965da1eb3f9ad4a5ce103cf6e32d35019e48
Reviewed-on: https://chromium-review.googlesource.com/c/1476105
Auto-Submit: Sidney San Martín <sdy@chromium.org>
Commit-Queue: Sidney San Martín <sdy@chromium.org>
Commit-Queue: Asanka Herath <asanka@chromium.org>
Reviewed-by: Asanka Herath <asanka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#632846}
2 files changed