Sketchy start at information on using files in gnulib.

for mktemp, need these files (including adding to EXTRA_DIST):
$GNULIBSRC/m4/check-decl.m4	m4
$GNULIBSRC/m4/mkstemp.m4	m4
$GNULIBSRC/m4/prereq.m4		m4
$GNULIBSRC/lib/tempname.c	lib
$GNULIBSRC/lib/mkstemp.c	lib

then in configure.ac:
AC_DEFUN([texinfo_MACROS],
[
  AC_REQUIRE([jm_PREREQ_TEMPNAME])dnl for mkstemp
  AC_REQUIRE([UTILS_FUNC_MKSTEMP])
])dnl
texinfo_MACROS