[PATCH] Revert the lsda change to scan_eh_tab.

[Albert Wong]

IIRC, we might end up revisiting this later when we clean up cxxabi.h for
EHABI. In EHABI, there isn't a _Unwind_GetLanguageSpecificData() and this
modification was necessary to share code. We can revisit if/when someone
gets to cleaning up cxxabi.h.

http://reviews.llvm.org/D4326