Replace ApiStrToNum uses with ApiLevel.

Test: treehugger
Bug: http://b/154667674
Change-Id: I2954bb21c1cfdeb305f25cfb6c8711c930f6ed50
diff --git a/java/aar.go b/java/aar.go
index 667dd9d..fcdd9c3 100644
--- a/java/aar.go
+++ b/java/aar.go
@@ -774,7 +774,8 @@
 	return a.depIsInSameApex(ctx, dep)
 }
 
-func (g *AARImport) ShouldSupportSdkVersion(ctx android.BaseModuleContext, sdkVersion int) error {
+func (g *AARImport) ShouldSupportSdkVersion(ctx android.BaseModuleContext,
+	sdkVersion android.ApiLevel) error {
 	return nil
 }