Fix bug in optOptimizeBools for equality of 0/1.

Fix bug in optOptimizeBools for equality of 0/1.

The method optIsBoolCond had a clever way to test for a constant
of value 0/1 by casting the resulting gtIconVal to (unsigned) and
comparing for <= 1. Unfortunately, for 64-bit targets gtIconVal as
ssize_t holds 64-bits and the cast to (unsigned) results in truncating
significant bits and results in the optimization falsely recognizing
legal patterns of bit-tests comparing against 0/1. Because 32-bit
targets represent 64-bit long constants as GT_CNS_LNG they do not
suffer from this problem as the code already had exclusions for them.

Commit migrated from https://github.com/dotnet/coreclr/commit/fbdd95218427aa9be25aaa7730f10e4707404c71