Allow building with javac 1.7

Change-Id: Id8d78558736482e10c52f2cc86a2b903b1fbdbe5

Author: LorDClockaN

core/main.mk

@@ -184,7 +184,7 @@ $(info $(space))
 $(info Please follow the machine setup instructions at)
 $(info $(space)$(space)$(space)$(space)https://source.android.com/source/download.html)
 $(info ************************************************************)
-$(error stop)
+#$(error stop)
 endif
 
 ifndef BUILD_EMULATOR