CMake: add target_link_libraries internally

Makes it easier to include glslang in a larger CMake project---instead
of having to call `target_link_libraries(glslang OSDependent OGLCompiler
HLSL)`, for example, you only need to call
`target_link_libraries(glslang)` and it will pull in the helpers it
needs.

This is also better in terms of cleaning up the "public interface",
of sorts, for building glslang: end-users probably shouldn't need to
know or be explicitly dependent on internal targets.

StandAlone/CMakeLists.txt

@@ -20,15 +20,10 @@ glslang_set_link_args(spirv-remap)
 
 set(LIBRARIES
     glslang
-    OGLCompiler
-    OSDependent
     SPIRV
     SPVRemapper
     glslang-default-resource-limits)
 
-if(ENABLE_HLSL)
-    set(LIBRARIES ${LIBRARIES} HLSL)
-endif(ENABLE_HLSL)
 
 if(WIN32)
     set(LIBRARIES ${LIBRARIES} psapi)