Add support for 256-bit return values for dirty helpers (amd64 only).
(Patrick J. LoPresti, lopresti@gmail.com).  Bug 294285.


git-svn-id: svn://svn.valgrind.org/vex/trunk@2743 8f6e269a-dfd6-0310-a8e1-e2731360e62c
mips64: Fix a problem with CCall.retty type.

Fix a problem when CCall needs to return 64 bits
for return type.


git-svn-id: svn://svn.valgrind.org/vex/trunk@2744 8f6e269a-dfd6-0310-a8e1-e2731360e62c