Simple refactoring of prefix related functions.

Rename the two prefix-in-list funcs so that their usages are clearer.
Also find and replace all the code that essentially does either.

This introduces additional loops in some places, but I think the added
readability and simplicity outweighs the performance degradation, which
should be negligible anyway.

Test: m nothing
Test: TreeHugger
Change-Id: I37e2276ca0c815105ed0031f23c0b1264b480e4f
diff --git a/android/arch.go b/android/arch.go
index fb1accc..73a490d 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -1521,12 +1521,7 @@
 
 // hasArmAbi returns true if arch has at least one arm ABI
 func hasArmAbi(arch Arch) bool {
-	for _, abi := range arch.Abi {
-		if strings.HasPrefix(abi, "arm") {
-			return true
-		}
-	}
-	return false
+	return PrefixInList(arch.Abi, "arm")
 }
 
 // hasArmArch returns true if targets has at least non-native_bridge arm Android arch