utf8.h: White-space only

I believe this makes the macro easier to read
utf8.c: Silence Win32 compiler warnings

The Win32 compiler doesn't realize that the values in these places can
be a max of 255.  Other compilers don't warn.
Revert "Optimise if/unless wrt OP_AND/OP_OR/OP_DOR. Also optimise OP_OR/OP_DOR chains."

This reverts commit 15a4d87479c14a0808c36a762bcd182890b84815
at the submitter's request.