Added diagnostics to phalcon_call_XXX()

See https://github.com/phalcon/cphalcon/pull/745#issuecomment-20315971

**Note:** the code is for Linux only. In theory should work for MacOS as well but I have no Mac to test.

For Mac all it will take is

```patch
-#ifdef linux 
+#if defined(linux) || defined(whatever is defined on mac)
```

For Windows this solution can probably be used: http://stackoverflow.com/a/5699483/1046773