[SemaCXX] Silence -Wconstant-logical-operand if the operand is a 0/1 from a macro.

Libraries specify enabled/disabled features using macro defs of 0/1, in such cases the -Wconstant-logical-operand
is noise.

rdar://15410291

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@207386 91177308-0d34-0410-b5e6-96231b3b80d8