Update flags passed to kotlinc

- Remove -Xuse-ir as it is default in Kotlin 1.5
- Add -Xsam-conversions=class for KT-46512

Change-Id: Ie351bb9ad5ec51ef7b7346d0076868d04cfe9811

java/base.go

@@ -895,8 +895,8 @@ func (j *Module) compile(ctx android.ModuleContext, aaptSrcJar android.Path) {
 		kotlincFlags := j.properties.Kotlincflags
 		CheckKotlincFlags(ctx, kotlincFlags)
 
-		// Dogfood the JVM_IR backend.
-		kotlincFlags = append(kotlincFlags, "-Xuse-ir")
+		// Workaround for KT-46512
+		kotlincFlags = append(kotlincFlags, "-Xsam-conversions=class")
 
 		// If there are kotlin files, compile them first but pass all the kotlin and java files
 		// kotlinc will use the java files to resolve types referenced by the kotlin files, but