library/string.m:
Add functions for converting uint64s to strings of base 8 or base 16
digits. For most integer types we can cast to a uint and then use the
uint versions of these operations but for 64-bit types we cannot since
on some of our supported platforms uints are 32-bit.
NEWS:
Announce the additions.
tests/hard_coded/Mmakefile:
tests/hard_coded/uint64_string_conv.{m,exp}:
Add a test of the new functions.
