Two bug fixes:

Two bug fixes:
 1. Actually increment the Statistic for the GV elim optzn
 2. When resolving undef branches, only resolve branches in executable blocks,
    avoiding marking a bunch of completely dead blocks live.  This has a big
    impact on the quality of the generated code.

With this patch, we positively rip up vortex, compiling Ut_MoveBytes to a
single memcpy call. In vortex we get this:

     12 ipsccp           - Number of globals found to be constant
    986 ipsccp           - Number of arguments constant propagated
   1378 ipsccp           - Number of basic blocks unreachable
   8919 ipsccp           - Number of instructions removed

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18796 91177308-0d34-0410-b5e6-96231b3b80d8