external: Update external reference commit ID
external: Update external reference commit ID

Update glslang to latest.

Change-Id: I2d235b4282a61764949105b1b76ff9d1cddc204a

KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers