bug 707577 - add fast-package target for mobile/android. r=khuey

mobile/android/build.mk

@@ -72,6 +72,9 @@ installer:
 package:
 	@$(MAKE) -C mobile/android/installer
 
+fast-package:
+	@$(MAKE) package MOZ_FAST_PACKAGE=1
+
 ifeq ($(OS_TARGET),Android)
 ifeq ($(MOZ_ANDROID_INSTALL_TARGET),)
 # Determine if there's more than one device connected

mobile/xul/build.mk

@@ -71,7 +71,7 @@ package:
 	@$(MAKE) -C mobile/xul/installer
 
 fast-package:
-	@MOZ_FAST_PACKAGE=1 $(MAKE) package
+	@$(MAKE) package MOZ_FAST_PACKAGE=1
 
 install::
 	@echo "Mobile can't be installed directly."