tree d89d97c805b44a773342ade6a7d6686d4fb243f8
parent 3604be156c1e297145cf10bd7057b5504fd35588
author Ben Clayton <bclayton@google.com> 1594124644 +0100
committer Ben Clayton <bclayton@google.com> 1594136659 +0100

Use CMake's builtin functionality for PCHs

`glslang_pch()` did manual mangling of the compiler flags to enable pre-compiled headers.
I couldn't get this approach to work with the `MachineIndependent` subdirectory, but fortunately CMake has added first-class support for precompiled headers in 3.16, which does work with subdirectories.

Moved `glslang_pch()` to the other global function declarations.

`glslang_pch()` is a no-op when using CMake earlier than `3.16`.

CMake's PCH implementation does not need the `pch.cpp` files, so just remove them.