Add code to UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly

Add code to UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly
to handle an addition class of early-return instructions we find in arm code:
tail-call optimziation returns where we restore the register state from the
function entry and jump directly (not branch & link) to another function --
when that other function returns, it will return to our caller.

Previously this mid-function epilogue sequence was not being correctly detected.
We would not re-instate the prologue setup instructions for the rest of the function
so unwinds would break from that point until the end of the function.
<rdar://problem/12502597>

llvm-svn: 166081