PrintDlgEx [1/7]: Add common failure checks and a trace.

[Juan Lang]

Hi Gal,

+ * This function is necessary in order to match the behaviour on
+ * Windows, which seems to do all these checks when PrintDlgEx
+ * is called. It is also necessary in order to replicate a bug in
+ * PrintDlgExA, where S_OK is returned for invalid DevMode or DevNames.

A test case would be a lot nicer than a comment.
--Juan