Work-around for crt objects with sdk: current

Test: convert libcups from Android.mk->Android.bp, mm -j64.

Change-Id: I4fddcfa5806d0ce27a229c37a078b0d93e9082a8
diff --git a/cc/binary.go b/cc/binary.go
index cd440ea..e982329 100644
--- a/cc/binary.go
+++ b/cc/binary.go
@@ -122,7 +122,7 @@
 				// version.
 				version := ctx.sdkVersion()
 				if version == "current" {
-					version = ctx.AConfig().PlatformSdkVersion()
+					version = getCurrentNdkPrebuiltVersion(ctx)
 				}
 
 				if binary.static() {