Add support for aapt2 png compression level

aapt2 by default uses the slowest compression level for png
images, and it makes sense for the final release. On the other
hand, it takes ~5x longer than zlib level 6 which is still
just ~1-2% larger for Framework resources. Allowing faster
compression saves over a minute of Platform compilation time
for eng builds, so let's support it

Test: manual, build + boot Android
Flag: EXEMPT build system feature disabled without uses
Change-Id: I74462c182ab78e37647f1dfe1ec5f449458e5dc1
diff --git a/android/util.go b/android/util.go
index 3fc4608..30d8ec6 100644
--- a/android/util.go
+++ b/android/util.go
@@ -308,6 +308,20 @@
 	return
 }
 
+// FilterListByPrefixes performs the same splitting as FilterList does, but treats the passed
+// filters as prefixes
+func FilterListByPrefix(list []string, filter []string) (remainder []string, filtered []string) {
+	for _, l := range list {
+		if HasAnyPrefix(l, filter) {
+			filtered = append(filtered, l)
+		} else {
+			remainder = append(remainder, l)
+		}
+	}
+
+	return
+}
+
 // FilterListPred returns the elements of the given list for which the predicate
 // returns true. Order is kept.
 func FilterListPred(list []string, pred func(s string) bool) (filtered []string) {