pass original CFLAGS

Change-Id: I1a2e9d41226822934b64ad31a61c816b3163a9ed
diff --git a/external/lcms2/ExternalProject_lcms2.mk b/external/lcms2/ExternalProject_lcms2.mk
index 981c1e6..fec0c36 100644
--- a/external/lcms2/ExternalProject_lcms2.mk
+++ b/external/lcms2/ExternalProject_lcms2.mk
@@ -30,7 +30,7 @@ $(call gb_ExternalProject_get_state_target,lcms2,build):
			$(if $(CROSS_COMPILING),--build=$(BUILD_PLATFORM) --host=$(HOST_PLATFORM) \
			$(if $(filter INTEL ARM,$(CPUNAME)),ac_cv_c_bigendian=no)) \
			CPPFLAGS=" $(SOLARINC)" \
			CFLAGS='$(if $(debug),$(gb_DEBUG_CFLAGS),$(gb_COMPILEROPTFLAGS))' \
			CFLAGS='$(CFLAGS) $(if $(debug),$(gb_DEBUG_CFLAGS),$(gb_COMPILEROPTFLAGS))' \
			$(if $(filter-out WNTGCC,$(OS)$(COM)),,CPPFLAGS=" -DCMS_DLL_BUILD") \
			$(if $(DISABLE_DYNLOADING), \
				--enable-static --disable-shared \