* memmem.c: New file, from gnulib.
* configure.ac: Add memmem to list of functions provided if they
are not available on the host.
* Makefile.in: Rebuild dependencies.
(CFILES): Add memmem.c.
(CONFIGURED_OFILES): Add memmem.o.
* configure, config.in, functions.texi: Rebuild.
From-SVN: r145139
