xfreerdp: smart sizing fix

Standard format PictStandardRGB24 is not always available.
Use XRenderFindVisualFormat instead of XRenderFindStandardFormat
Merge pull request #2253 from nfedera/fix-2014-12-04-02

xfreerdp: smart sizing fix
Merge branch 'master' of github.com:FreeRDP/FreeRDP