This is gawkextlib.  It contains several shared library extension packages
for gawk, as well as libgawkextlib containing some APIs that are useful
for extension packages.

This package contains the following gawk shared libraries:
   xml
   pgsql
   gd
   mpfr (but please compare to using gawk's new -M flag)

The libgawkextlib library contains the strhash API used by pgsql and gd,
and the gawk_varinit API to make it easy to initialize variables (used
by XML and MPFR).

To use this library, you must first build the new version of gawk
containing shared extension library support.  Here is a recipe:

   git clone git://git.savannah.gnu.org/gawk.git
   cd gawk
   ./bootstrap.sh
   ./configure --prefix=/tmp/newgawk
   make && make check && make install

After you build and install that in /tmp/newgawk, you can then build
libgawk like so:

Using git:
   git clone git://git.code.sf.net/p/gawkextlib/code gawkextlib
   cd gawkextlib
   ./update-autotools

Or it may be easier from a tarball if you do not have current autotools
installed:
   tar xf gawkextlib-<version>.tar.gz
   cd gawkextlib-<version>

Either way, the steps to build are the same:
   ./configure --with-gawk=/tmp/newgawk --prefix=/tmp/newgawk
   make && make check && make install

N.B. On an rpm-based system, if gawk and gawk-devel rpms have been installed
(which is unlikely, since they don't really exist yet), you can simply say:
   rpmbuild -tb gawkextlib-<version>.tar.gz