Add myself to Windows MinGW maintainers

Originally committed as revision 9463 to svn://svn.ffmpeg.org/ffmpeg/trunk

MAINTAINERS

@@ -256,6 +256,6 @@ i386                                    Michael Niedermayer
 Mac OS X / PowerPC                      Romain Dolbeau, Guillaume Poirier
 Amiga / PowerPC                         Colin Ward
 Linux / PowerPC                         Luca Barbato
-Windows MinGW                           Alex Beregszaszi
+Windows MinGW                           Alex Beregszaszi, Ramiro Polla
 Windows Cygwin                          Victor Paesa
 ADI/Blackfin DSP                        Marc Hoffman