Blender Git Loki

Clang-Tidy: Allow use with GCC but warn about possible failure

The compilation using GCC + Clang-Tidy succeeded for me and Sybren
(with some linker caveats for Sybren) but seems that it is doable
to make GCC + Clang-Tidy to officially work for Blender.

Now it should be possible to enable Clang-Tidy doing something like

make developer debug BUILD_CMAKE_ARGS='-DWITH_CLANG_TIDY=ON'