Keep the stack properly 16-aligned when delivering signals on
amd64-darwin.  Fixes the failure shown in 
https://bugs.kde.org/show_bug.cgi?id=254646#c13



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@12461 a5019735-40e9-0310-863c-91ae7b9d1cf9
1 file changed