This commit fixes the unw_step() for ARM EHABI. However, this commit
also changes the implementation details for ARM EHABI.
The first change is that the personality function should call
__gnu_unwind_frame() for default (or de facto) frame unwinding based on
the ARM-defined unwind opcode. The function __gnu_unwind_frame() will
in turn calls unw_step() which actually unwinds the frame.
The second change is that the implementation _Unwind_Backtrace() should
no longer calls unw_step() to unwind the frame; since according to ARM
EHABI, the personality function should unwind the frame for us.
Special thanks to Anton for helpful suggestion on the initial version of
this patch.
llvm-svn: 238560
Logan Chien