Makefile: skip .d inclusion for 'testdata' target

avoids some unnecessary work when pulling testdata in a freshly
configured tree

Change-Id: Ib43379b0e1549107f3f1b227afca49a899bcc3ab

build/make/Makefile

@@ -330,7 +330,10 @@ endef
 ifneq ($(target),)
 include $(SRC_PATH_BARE)/$(target:-$(TOOLCHAIN)=).mk
 endif
-ifeq ($(filter %clean,$(MAKECMDGOALS)),)
+
+skip_deps := $(filter %clean,$(MAKECMDGOALS))
+skip_deps += $(findstring testdata,$(MAKECMDGOALS))
+ifeq ($(strip $(skip_deps)),)
   # Older versions of make don't like -include directives with no arguments
   ifneq ($(filter %.d,$(OBJS-yes:.o=.d)),)
     -include $(filter %.d,$(OBJS-yes:.o=.d))