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.

glslang/CMakeLists.txt

@@ -82,6 +82,10 @@ set(HEADERS
 
 add_library(glslang STATIC ${BISON_GLSLParser_OUTPUT_SOURCE} ${SOURCES} ${HEADERS})
 set_property(TARGET glslang PROPERTY FOLDER glslang)
+target_link_libraries(glslang OGLCompiler OSDependent)
+if(ENABLE_HLSL)
+	target_link_libraries(glslang HLSL)
+endif()
 
 if(WIN32)
     source_group("Public" REGULAR_EXPRESSION "Public/*")