Fix big-endian codegen bug. We're splitting up

Fix big-endian codegen bug.  We're splitting up
overly long ints, e.g. i96, into pieces at PHIs
and the nodes that feed into them; however big-endian
reverses the order of the pieces (for some reason), and
wasn't doing it the same way on both sides, so
the pieces didn't match and runtime failures ensued.
Fixes 188.ammp and sqlite3 on ppc32.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65481 91177308-0d34-0410-b5e6-96231b3b80d8