Correct bug-number in ChangeLog.

Correct bug-number in ChangeLog.

        PR libstdc++/51135
        * libsupc++/cxxabi.h (__cxxabi_dtor_type): New type.
        (__cxa_throw): Use it for destructor-argument.
        * libsupc++/eh_throw.cc (__cxa_throw): Likewise.
        * libsupc++/unwind-cxx.h (__cxa_exception): Change type of member
        exceptionDestructor to __cxxabi_dtor_type.
        * config/os/mingw32-w64/os_defines.h (_GLIBCXX_USE_THISCALL_ON_DTOR):
        Define.
        (__cxa_dtor_type): Declare target secific type variant.
        * config/os/mingw32/os_defines.h: Likewise.

From-SVN: r182238