Revert r320124 "Fold together the in-range and out-of-range portions of -Wtautological-compare."

This broke Chromium:

../../base/trace_event/trace_log.cc:1545:29: error: comparison of constant 64
with expression of type 'unsigned int' is always true
[-Werror,-Wtautological-constant-out-of-range-compare]
  DCHECK(handle.event_index < TraceBufferChunk::kTraceBufferChunkSize);
         ~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The 'unsigned int' is really a 6-bit bitfield, which is why it's always
less than 63.

Did this use to fall under the "in-range" case before? I thought we
didn't use to warn when comparing against the boundaries of a type.

llvm-svn: 320133