Rework InstrTypes.h so to reduce the repetition around the NSW/NUW/Exact

versions of creation functions.  Eventually, the "insertion point" versions
of these should just be removed, we do have IRBuilder afterall.

Do a massive rewrite of much of pattern match.  It is now shorter and less
redundant and has several other widgets I will be using in other patches.
Among other changes, m_Div is renamed to m_IDiv (since it only matches 
integer divides) and m_Shift is gone (it used to match all binops!!) and
we now have m_LogicalShift for the one client to use.

Enhance IRBuilder to have "isExact" arguments to things like CreateUDiv
and reduce redundancy within IRbuilder by having these methods chain to
each other more instead of duplicating code.

llvm-svn: 125194