Configuration does not fail when gnulib is not installed

[kyselejsyrecek]

Due to an error in Autoconf source at

pam_tacplus/configure.ac

Lines 25 to 32 in b89dba4

	AC_CHECK_PROG([GNULIB], [gnulib-tool], [gnulib-tool], [
	Gnulib is required to compile this program. On Ubuntu Focal you can run "apt install gnulib", but
	most other systems will ship a very old version so you fetch it from GNU repository:
	git clone https://git.savannah.gnu.org/git/gnulib.git \$HOME/gnulib
	export PATH=\$PATH:\$HOME/gnulib
	])

configuration does not fail when gnulib is not installed. Excerpt from the output:

checking for gnulib-tool... install: missing destination file operand after 'gnulib, but'$'\n''most other systems will ship a very old version so you fetch it from GNU repository:'$'\n\n''git clone https://git.savannah.gnu.org/git/gnulib.git $HOME/gnulib'$'\n''export PATH=$PATH:$HOME/gnulib'$'\n\n'
Try 'install --help' for more information.
no
checking for aarch64-linux-gcc... (cached) gcc
checking whether the compiler supports GNU C... (cached) yes