fix libraries needed

Index: libshaderc/CMakeLists.txt
--- libshaderc/CMakeLists.txt.orig
+++ libshaderc/CMakeLists.txt
@@ -102,7 +102,7 @@ endif(SHADERC_ENABLE_INSTALL)
 
 shaderc_add_tests(
   TEST_PREFIX shaderc_combined
-  LINK_LIBS shaderc_combined ${CMAKE_THREAD_LIBS_INIT}
+  LINK_LIBS shaderc_combined ${SHADERC_LIBS}
   INCLUDE_DIRS include ${shaderc_SOURCE_DIR}/libshaderc_util/include ${glslang_SOURCE_DIR}
                ${spirv-tools_SOURCE_DIR}/include
                ${SPIRV-Headers_SOURCE_DIR}/include
