Replace SortedStringKeys with SortedKeys

Now that we have generics.

Bug: 193460475
Test: presubmits
Change-Id: I1594fd8feb505175d5c09c03ef397e5ffd5b09cb
diff --git a/bp2build/configurability.go b/bp2build/configurability.go
index 2a0a78e..8e17103 100644
--- a/bp2build/configurability.go
+++ b/bp2build/configurability.go
@@ -256,7 +256,7 @@
 	}
 
 	var selects string
-	for _, selectKey := range android.SortedStringKeys(selectMap) {
+	for _, selectKey := range android.SortedKeys(selectMap) {
 		if selectKey == bazel.ConditionsDefaultSelectKey {
 			// Handle default condition later.
 			continue