[NFC] Replace -1U{LL} expressions with appropriate *_MAX macros in Support library.

This makes a code a bit more clear and also gets rid of C4146 warning
on MSVC compiler:
 'unary minus operator applied to unsigned type, result still unsigned'.

In case uint64_t variable is initialized or compared against -1U expression,
which corresponds to 32-bit constant, UINT_MAX macro is used to preserve
NFC semantics; -1ULL is replaced with UINT64_MAX.

Reviewed By: dblaikie, craig.topper

Differential Revision: https://reviews.llvm.org/D143942