Fix undefined behavior in the macros SET_BH, CLEAR_BH, & ISSET_BH

Fix undefined behavior in the macros SET_BH, CLEAR_BH, & ISSET_BH

These macros contain this pattern:
1 << ((Int32_value) & 31

This causes the undefined behavior sanitizers in clang and gcc to
complain because the shift, while ultimately stored to an unsigned
variable, is done as a signed value. Adding a cast to unsigned for
the int32 value resolves this issue.