dev-util/glslang: Fix pre-compiled header race

BUG=b:259102548
TEST=Run `FEATURES=noclean emerge-$BOARD glslang`.
     Confirm no pch files are built.

(cherry picked from commit c31d63e1815f96b1a31c3ee16ec7e4cf4e8b30d8)

Change-Id: I1716fa45b03e359f454a9d204985c7d5951d274e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/4091163
Owners-Override: Aaron Massey <aaronmassey@google.com>
Tested-by: Aaron Massey <aaronmassey@google.com>
Commit-Queue: Aaron Massey <aaronmassey@google.com>
Reviewed-by: Aaron Massey <aaronmassey@google.com>
1 file changed