darwin universal builds need BUILD_PFX
Universal builds create subdirectories for each target. Without
BUILD_PFX we only generated one vpx_rtcd.h instead of one for each.
Change-Id: I1caed4e018c8865ffc8da15e434cae2b96154fb4
diff --git a/libs.mk b/libs.mk
index b77276e..5889a88 100644
--- a/libs.mk
+++ b/libs.mk
@@ -329,8 +329,8 @@
#
# Rule to generate runtime cpu detection files
#
-$(OBJS-yes:.o=.d): vpx_rtcd.h
-vpx_rtcd.h: $(SRC_PATH_BARE)/$(sort $(filter %rtcd_defs.sh,$(CODEC_SRCS)))
+$(OBJS-yes:.o=.d): $(BUILD_PFX)vpx_rtcd.h
+$(BUILD_PFX)vpx_rtcd.h: $(SRC_PATH_BARE)/$(sort $(filter %rtcd_defs.sh,$(CODEC_SRCS)))
@echo " [CREATE] $@"
$(qexec)$(SRC_PATH_BARE)/build/make/rtcd.sh --arch=$(TGT_ISA) \
--sym=vpx_rtcd \