collect emm meta files for emma instrumented build

when doing 'make dist', with EMMA_INSTRUMENT on the coverage.em files
generated for each module will be collected into one emma_meta.zip file

Change-Id: I382c39a97005e6cae5c79ad7eaef1c8857f658af
diff --git a/core/main.mk b/core/main.mk
index 3ffb084..1fd546e 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -705,6 +705,12 @@
 	$(INSTALLED_RAMDISK_TARGET) \
  )
 
+ifeq ($(EMMA_INSTRUMENT),true)
+$(call dist-for-goals, droid, \
+	$(EMMA_META_ZIP) \
+ )
+endif
+
 # Tests are installed in userdata.img.  If we're building the tests
 # variant, copy it for "make tests dist".  Also copy a zip of the
 # contents of userdata.img, so that people can easily extract a