change the new isel matcher to emit ComplexPattern matches

change the new isel matcher to emit ComplexPattern matches
as the very last thing before node emission.  This should
dramatically reduce the number of times we do 'MatchAddress'
on X86, speeding up compile time.  This also improves comments
in the tables and shrinks the table a bit, now down to
80506 bytes for x86.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97703 91177308-0d34-0410-b5e6-96231b3b80d8