[ios7/ios/atv2] - link statically against libmpeg2 - since ios7 we crash...

... and burn when we load libmpeg2 as dylib - closes #14813

Fix for carsh&burn when dyloading libmpeg2 on ios7. We now statically link on ios.

Fixes trac ticket http://trac.xbmc.org/ticket/14813

@all xcode junkies - it seems that adding linker flags (like -lxslt) in the tools/darwin/Configurations/App-iOS.xcconfig file don't make it completly to the atv2 target (the atv2 xcconfig includes the ios one - maybe that indirection is a problem). I think this is a error with xcode3 - so for now - if anyone adds a new lib we need to link statically against - please add the additional -l to the atv2 target of the xcode project aswell.

Especially on atv2 we don't see the linker error because we have to link lazy (because of missing SDK libs - there is no atv2 sdk - which are only available at runtime on the device).

@diederich any idea (i know when xcode3 was current you weren't born yet) whats up with this atv2 target? ^^