libdfp: Fixes for BID left_justify
libdfp: Enable BID for 32bits

This patch add BID support for 32 bits.  64 bits support relies on int
128 bits operations which is supplied by GCC/clang extension
__uint128_t.  Some architectures, however, does not support this
extension (x86 32 bits, for instance).

So on BID 32 bits the mini-gmp implementation from libgmp is used.
Currently it is included direct in libdecnumber/decimal128.c object and
thus used in other parts of libdfp through libdecnumber.a static
library.

The mini-gmp is a multiprecision library that works on limbs of 32 bits.
libdfp: Remove libbid files

With BID support in libdecnumber, there is no need to keep libbid files.
libdecnumber: Fix decDebug64 extension
libdfp: Fix bid-private warning in 32-bits