Fixed warning.

tools/shaderc/shaderc_spirv.cpp

@@ -9,6 +9,7 @@ BX_PRAGMA_DIAGNOSTIC_PUSH()
 BX_PRAGMA_DIAGNOSTIC_IGNORED_MSVC(4100) // error C4100: 'inclusionDepth' : unreferenced formal parameter
 BX_PRAGMA_DIAGNOSTIC_IGNORED_MSVC(4265) // error C4265: 'spv::spirvbin_t': class has virtual functions, but destructor is not virtual
 BX_PRAGMA_DIAGNOSTIC_IGNORED_CLANG_GCC("-Wshadow") // warning: declaration of 'userData' shadows a member of 'glslang::TShader::Includer::IncludeResult'
+#define ENABLE_OPT 1
 #include <ShaderLang.h>
 #include <ResourceLimits.h>
 #include <SPIRV/SPVRemapper.h>