Add explanation of Linux to windows cross compiling to REAME.
Add explanation of Linux to windows cross compiling to REAME.

git-svn-id: a21e2c1a9f1a66aa2b49a2fb7314df0f83771e9b@14726 0101bb08-14d6-0310-b084-bc0e0c8e3800

soundcloud/ogg,svn2github/ogg,svn2github/libogg,soundcloud/ogg,peterdocter/ogg,fcoulombe/ogg,fcoulombe/ogg,peterdocter/ogg,svn2github/ogg,svn2github/libogg