Disable Bash completion in 'make distcheck'

We cannot rely on the auto-detection of Bash completion dir during 'make
distcheck' because autotools does not use DESTDIR, only --prefix for the
install check, and pkg-config returns a system path.

Also, show detected path in configure summary for debug.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

Makefile.am

@@ -34,6 +34,7 @@ release: distcheck
 		printf "$$file.sha256\t"; cat ../$$file.sha256 | cut -f1 -d' ';	\
 	done
 
-DISTCHECK_CONFIGURE_FLAGS = --prefix=/usr --sysconfdir=/etc --localstatedir=/var \
-			    --enable-testserv-plugin --enable-x11-common-plugin  \
-			    --with-watchdog --with-keventd --with-fstab=/etc/fstab
+DISTCHECK_CONFIGURE_FLAGS = --prefix=/usr --sysconfdir=/etc --localstatedir=/var   \
+			    --enable-testserv-plugin --enable-x11-common-plugin    \
+			    --with-watchdog --with-keventd --with-fstab=/etc/fstab \
+			    --with-bash-completion-dir=no