[Bug libstdc++/47913] [C++0x] improve ratio_add to overflow less often

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47913

--- Comment #23 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-05-04 17:56:19 UTC ---
Nit (for the future): library patches are diffed from where the library
ChangeLog is.