build: Fix mingw crashes in libdvdread when using gcc >= 4.7
mingw gcc >= 4.7 now packs structures in a "MS compatible" fashion.
This breaks the normal expected behavior of packed structures.  To restore
the correct behavior, the option -mno-ms-bitfields must be added :-\


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@5208 b64f7644-9d1e-0410-96f1-a4d463321fa5