Added a new development target api.

Change-Id: I71a16597f2605b9323424f8d493f103519d10178
diff --git a/slang_backend.h b/slang_backend.h
index 4254aca..834c49a 100644
--- a/slang_backend.h
+++ b/slang_backend.h
@@ -81,7 +81,7 @@
 
   PragmaList *mPragmas;
 
-  virtual unsigned int getTargetAPI() const {
+  virtual int getTargetAPI() const {
     return SLANG_MAXIMUM_TARGET_API;
   }