Collect the GPL source files.

Bug: 5693205
Change-Id: I045b83949f8b29d7c5cf5c0ab32c5b83cf398e71
diff --git a/core/base_rules.mk b/core/base_rules.mk
index 242b53d..66d2465 100644
--- a/core/base_rules.mk
+++ b/core/base_rules.mk
@@ -110,8 +110,10 @@
 # find files like MODULE_LICENSE_GPL_AND_AFL but exclude files like
 # MODULE_LICENSE_LGPL.
 #
-ifneq ($(call find-parent-file,$(LOCAL_PATH),MODULE_LICENSE*_GPL* MODULE_LICENSE*_MPL*),)
+gpl_license_file := $(call find-parent-file,$(LOCAL_PATH),MODULE_LICENSE*_GPL* MODULE_LICENSE*_MPL*)
+ifneq ($(gpl_license_file),)
   LOCAL_MODULE_TAGS += gnu
+  ALL_GPL_MODULE_LICENSE_FILES := $(sort $(ALL_GPL_MODULE_LICENSE_FILES) $(gpl_license_file))
 endif
 
 #