Fix filter rule when checking for apks in PRODUCT_COPY_FILES.

PRODUCT_COPY_FILES entries can include the src:dest:owner
syntax versus src:dest. This causes the filter to miss
certain cases. Instead use the word-colon function to
grab the dest regardless of syntax.

Change-Id: I1f4e57a236c1db148bada0cfe5bd1e87bb1194d6
Signed-off-by: rpcraig <rpcraig@tycho.ncsc.mil>
diff --git a/core/Makefile b/core/Makefile
index 2bcf0cf..e99f49d 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -20,7 +20,7 @@
 # src:dest pair is the first one to match the same dest"
 #$(1): the src:dest pair
 define check-product-copy-files
-$(if $(filter %.apk, $(1)),$(error \
+$(if $(filter %.apk, $(call word-colon, 2, $(1))),$(error \
     Prebuilt apk found in PRODUCT_COPY_FILES: $(1), use BUILD_PREBUILT instead!))
 endef
 # filter out the duplicate <source file>:<dest file> pairs.