Turn on the new isel by default. Here are some fun numbers

Turn on the new isel by default.  Here are some fun numbers
with a release-asserts build on x86-64-darwin10:

LLC Size:
Old: 15,426,852
New: 12,759,140  (down 2.7M)

LLI Size:
Old: 9,926,876
New: 8,864,292   (down 1.1M)

X86ISelDAGToDAG.o size:
Old: 1,401,232
New:   162,868   (down 1.3M)

Time to build X86ISelDAGToDAG.o:
Old: 67.147u 2.060s 1:09.78
New:  4.234u 0.387s 0:04.77

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97475 91177308-0d34-0410-b5e6-96231b3b80d8