Add LOCAL_DONT_DELETE_JAR_META_INF

To support to not delete META_INF directory from the static Java
libraries.

Change-Id: I720bfa059c43dd457a74a0c60bb6797aa408ecaf
diff --git a/core/definitions.mk b/core/definitions.mk
index bc4886c..94a116c 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -1437,8 +1437,8 @@
       exit 1; \
     fi; \
     unzip -qo $$f -d $(2); \
-    (cd $(2) && rm -rf META-INF); \
-  done
+  done \
+  $(if $(PRIVATE_DONT_DELETE_JAR_META_INF),,;rm -rf $(2)/META-INF)
 endef
 
 # Common definition to invoke javac on the host and target.