Use agreed upon include paths for spirv-cross (#795)
Use agreed upon include paths for spirv-cross (#795)

All other projects using spirv-cross include it using <spirv_msl.hpp>
for example. Follow that convention so we can more easily integrate with
other projects.
antiagainst/shaderc,antiagainst/shaderc,antiagainst/shaderc,antiagainst/shaderc