DRY setup_build.cmake's use of find_host_program.
DRY setup_build.cmake's use of find_host_program.

antiagainst/shaderc,dneto0/shaderc,fuchsia-mirror/third_party-shaderc,fuchsia-mirror/third_party-shaderc,AWoloszyn/shaderc,antiagainst/shaderc,AWoloszyn/shaderc,antiagainst/shaderc,antiagainst/shaderc,dneto0/shaderc,dneto0/shaderc,Qining/shaderc,Qining/shaderc,fuchsia-mirror/third_party-shaderc,Qining/shaderc,AWoloszyn/shaderc,dneto0/shaderc