contrib: fix deprecated GCC compiler options.

-mcpu has been deprecated in favor of -mtune; also, -Wstrict-prototypes was causing build failures on some systems.

Patch by icchan. Thanks!


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@5917 b64f7644-9d1e-0410-96f1-a4d463321fa5