This updates gnulib to a relatively recent commit. Most of this was
done by the gnulib import script; the only change I made was to
update-gnulib.sh.
Tested on x86-64 Fedora 34. I also did a mingw cross build.
This fixes PR27184, a failure to compile gdb due to
cdefs.h being out of sync with glibc on ppc64le targets
which are compiled with -mabi=ieeelongdouble and glibc
2.32.
Likewise, update usage of _GL_ATTRIBUTE_FORMAT_PRINTF to
_GL_ATTRIBUTE_FORMAT_PRINTF_STANDARD.
Likewise, disable newly added rpl_free gnulib api in
gdbserver support libraries.
Likewise, undefine read/write macros before redefining them
on mingw targets.
Likewise, wrap C++ usage of free with GNULIB_NAMESPACE namespace
as needed.
Change-Id: I86517613c0d8ac8f5ea45bbc4ebe2b54a3aef29f
