win32/common/gstconfig.h: removed libxml include directive
win32/common/gstconfig.h: removed libxml include directive

This is a leftover from 0.10 and not needed anymore.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=745210

StreamUtils/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,centricular/gstreamer,centricular/gstreamer,StreamUtils/gstreamer,shelsonjava/gstreamer,krichter722/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,StreamUtils/gstreamer,krichter722/gstreamer,jpxiong/gstreamer,centricular/gstreamer,jpxiong/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,mparis/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,krichter722/gstreamer,mparis/gstreamer,shelsonjava/gstreamer,krichter722/gstreamer,shelsonjava/gstreamer,krichter722/gstreamer,centricular/gstreamer,jpxiong/gstreamer,mparis/gstreamer,jpxiong/gstreamer