propagate user-set CFLAGS to build

Change-Id: I6c9d8ff064f059e4a756593ff5c45b9670cacb29

external/redland/ExternalProject_raptor.mk

@@ -35,7 +35,7 @@ else
 $(call gb_ExternalProject_get_state_target,raptor,build):
 	$(call gb_ExternalProject_run,build,\
 		$(if $(filter IOS,$(OS)),LIBS="-liconv") \
-		CFLAGS="$(if $(debug),-g,-O) $(if $(filter TRUE,$(DISABLE_DYNLOADING)),-fvisibility=hidden) \
+		CFLAGS="$(CFLAGS) $(if $(debug),-g,-O) $(if $(filter TRUE,$(DISABLE_DYNLOADING)),-fvisibility=hidden) \
 			$(if $(filter GCCLINUXPOWERPC64,$(COM)$(OS)$(CPUNAME)),-mminimal-toc)" \
 		LDFLAGS=" \
 			$(if $(filter LINUX FREEBSD,$(OS)),-Wl$(COMMA)-z$(COMMA)origin -Wl$(COMMA)-rpath$(COMMA)\\"\$$\$$ORIGIN") \

external/redland/ExternalProject_rasqal.mk

@@ -41,7 +41,7 @@ $(call gb_ExternalProject_get_state_target,rasqal,build):
 else
 $(call gb_ExternalProject_get_state_target,rasqal,build):
 	$(call gb_ExternalProject_run,build,\
-		CFLAGS="$(if $(filter TRUE,$(DISABLE_DYNLOADING)),-fvisibility=hidden)" \
+		CFLAGS="$(CFLAGS) $(if $(filter TRUE,$(DISABLE_DYNLOADING)),-fvisibility=hidden)" \
 		LDFLAGS=" \
 			$(if $(filter LINUX FREEBSD,$(OS)),-Wl$(COMMA)-z$(COMMA)origin -Wl$(COMMA)-rpath$(COMMA)\\"\$$\$$ORIGIN") \
 			$(if $(SYSBASE),$(if $(filter LINUX SOLARIS,$(OS)),-L$(SYSBASE)/lib -L$(SYSBASE)/usr/lib -lpthread -ldl))" \

external/redland/ExternalProject_redland.mk

@@ -43,7 +43,7 @@ $(call gb_ExternalProject_get_state_target,redland,build):
 else
 $(call gb_ExternalProject_get_state_target,redland,build):
 	$(call gb_ExternalProject_run,build,\
-		CFLAGS="$(if $(filter TRUE,$(DISABLE_DYNLOADING)),-fvisibility=hidden)" \
+		CFLAGS="$(CFLAGS) $(if $(filter TRUE,$(DISABLE_DYNLOADING)),-fvisibility=hidden)" \
 		LDFLAGS=" \
 			$(if $(filter LINUX FREEBSD,$(OS)),-Wl$(COMMA)-z$(COMMA)origin -Wl$(COMMA)-rpath$(COMMA)\\"\$$\$$ORIGIN") \
 			$(if $(SYSBASE),$(if $(filter LINUX SOLARIS,$(OS)),-L$(SYSBASE)/lib -L$(SYSBASE)/usr/lib -lpthread -ldl))" \