GN: Fix duplicate include of VersionGLSL.h The duplicate include was confusing the MSVC project loader. Bug: None Change-Id: I3637d9f0f26272e77cf4ab723532f53e12c13f51 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3123227 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>