Add unstrippedOutputFilePath to the linker interface

Test: m
Change-Id: I85a0cbda6ebb9838451ed8c607c2087460b7b742

cc/cc.go

@@ -306,6 +306,7 @@ type linker interface {
 
 	link(ctx ModuleContext, flags Flags, deps PathDeps, objs Objects) android.Path
 	appendLdflags([]string)
+	unstrippedOutputFilePath() android.Path
 }
 
 type installer interface {
@@ -406,10 +407,8 @@ func (c *Module) OutputFile() android.OptionalPath {
 }
 
 func (c *Module) UnstrippedOutputFile() android.Path {
-	if library, ok := c.linker.(*libraryDecorator); ok {
-		return library.unstrippedOutputFile
-	} else if binary, ok := c.linker.(*binaryDecorator); ok {
-		return binary.unstrippedOutputFile
+	if c.linker != nil {
+		return c.linker.unstrippedOutputFilePath()
 	}
 	return nil
 }