Qualify CMake function names with "spvtools" to avoid conflictions.
Qualify CMake function names with "spvtools" to avoid conflictions.

If a third-party project defines a CMake function with the same
name, by importing that project's CMake configuration, we may end
up overwriting our own copy. Qualify all defined functions to
reduce that probability.

KhronosGroup/SPIRV-Tools,KhronosGroup/SPIRV-Tools,fuchsia-mirror/third_party-spirv-tools,dneto0/SPIRV-Tools,greg-lunarg/SPIRV-Tools,antiagainst/SPIRV-Tools,dneto0/SPIRV-Tools,LukasBanana/SPIRV-Tools,KhronosGroup/SPIRV-Tools,greg-lunarg/SPIRV-Tools,LukasBanana/SPIRV-Tools,pierremoreau/SPIRV-Tools,pierremoreau/SPIRV-Tools,antiagainst/SPIRV-Tools,KhronosGroup/SPIRV-Tools,dneto0/SPIRV-Tools,dneto0/SPIRV-Tools,dneto0/SPIRV-Tools,umar456/SPIRV-Tools,antiagainst/SPIRV-Tools,LukasBanana/SPIRV-Tools,pierremoreau/SPIRV-Tools,dneto0/SPIRV-Tools,pierremoreau/SPIRV-Tools,pierremoreau/SPIRV-Tools,pierremoreau/SPIRV-Tools,umar456/SPIRV-Tools,greg-lunarg/SPIRV-Tools,antiagainst/SPIRV-Tools,pierremoreau/SPIRV-Tools,pierremoreau/SPIRV-Tools,fuchsia-mirror/third_party-spirv-tools,fuchsia-mirror/third_party-spirv-tools,KhronosGroup/SPIRV-Tools,antiagainst/SPIRV-Tools,umar456/SPIRV-Tools,KhronosGroup/SPIRV-Tools,KhronosGroup/SPIRV-Tools,KhronosGroup/SPIRV-Tools,dneto0/SPIRV-Tools,dneto0/SPIRV-Tools