MSL: Print early_fragment_tests specifier before fragment
MSL: Print early_fragment_tests specifier before fragment

The compiler in 10.14 reports an error that the attribute cannot be
applied to types if the specifier is printed before fragment.

KhronosGroup/SPIRV-Cross,KhronosGroup/SPIRV-Cross,KhronosGroup/SPIRV-Cross,KhronosGroup/SPIRV-Cross,KhronosGroup/SPIRV-Cross,KhronosGroup/SPIRV-Cross