update rollers to to Khronos repos that now use "main" branch

Khronos repos are renaming their "master" branches to "main"

SPIRV-Tools and SPIRV-Headers have already been updated.

These have not:

https://github.com/KhronosGroup/glslang/issues/3107
https://github.com/KhronosGroup/Vulkan-Loader/issues/1107 
https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/5084

