turn down the logical bitwise confusion warning to not warn

turn down the logical bitwise confusion warning to not warn
when the RHS of the ||/&& is ever 0 or 1.  This handles a variety of
creative idioms for "true" used in C programs and fixes many false
positives at the expense of a few false negatives.  This fixes
rdar://8230351.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@109314 91177308-0d34-0410-b5e6-96231b3b80d8