lint support.

Bug: 6167394
$make lint-<app-name>       # to lint on a single module
$make lintall               # to lint on all packages in the source
                              tree.

Change-Id: I4decc76fb75793ce44809232b0ec72b766fbb434
diff --git a/core/main.mk b/core/main.mk
index 1ab9b6c..317660f 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -817,6 +817,8 @@
 )
 endif
 
+.PHONY: lintall
+
 .PHONY: samplecode
 sample_MODULES := $(sort $(call get-tagged-modules,samples))
 sample_APKS_DEST_PATH := $(TARGET_COMMON_OUT_ROOT)/samples