Update the checks in EmulateInstructionARM::GetFramePointerRegisterNumber

and EmulateInstructionARM::GetFramePointerDWARFRegisterNumber to recognize
the Apple arm convention (of using r7 for the frame pointer, regardless of
thumb or arm) even if the OS does not match Darwin/MacOSX/iOS.  Also 
corrects the behavior for thumb code on non-Apple platforms.
<rdar://problem/14661537> 

llvm-svn: 198648