[patch PR libstdc++/51135]: Fix [4.7 Regression] SIGSEGV during exception cleanup on win32

[Kai Tietz]

2011/12/12 Paolo Carlini <paolo.carlini@oracle.com>:
> PS: remember to adjust the Copyright years of eh_throw.cc and unwind-cxx.h.
> I would also mention the PR in the os_* files.
>
> Paolo.

Thanks for the reminder about copyright.  Added comment about pr and
added copyright year to files not mentioning 2011.
Applied at revision 182237.

Kai