win32, dos: Work around a bug in the GNU toolchain.

win32, dos: Work around a bug in the GNU toolchain.
The bug[1] is exposed when gcc decides to put some data in a common
section (i.e. data that will be used by more than one object). It will
suggest the data to be aligned, but binutils >= 2.19 will fail to
properly align it. Thus if the data requires any alignment greater
than 4, the application will crash.
The workaround prevents gcc from putting data in a common section,
instead putting it in a properly aligned section.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@18501 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b