Fix build flags for all arches (mtune should not be set by cmake)

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New package in fedora, imported from rpmfusion.

Changes from rpmfusion:

– Update to v2.0 Beta 3

– GTK frontend has been dropped in favour for wxGTK frontend

– Package name changes from *vbam-gtk* to *visualboyadvance-m* and *vbam-sdl* to *visualboyadvance-m-sdl*, removing common package

– Added appdata