Move the local m4 macros

The `aclocal' step is skipped during `autoreconf' because aclocal.m4 is
present.
Move the current aclocal.m4 which contains local macros into the m4/
folder. With this change the aclocal.m4 will be re-created during
changes to the m4/ macro.
This is needed so the `aclocal' can fetch m4 macros from the system if
they are references in the configure script. This is a prerequisite to
use PKG_CHECK_MODULES.

Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>

Makefile.in

@@ -187,7 +187,7 @@ $(SSHOBJS): Makefile.in config.h
 $(SSHDOBJS): Makefile.in config.h
 configure-check: $(srcdir)/configure
 
-$(srcdir)/configure: configure.ac aclocal.m4
+$(srcdir)/configure: configure.ac $(srcdir)/m4/*.m4
 	@echo "ERROR: configure is out of date; please run ${AUTORECONF} (and configure)" 1>&2
 	@exit 1
 

configure.ac

@@ -14,6 +14,7 @@
 # OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
 AC_INIT([OpenSSH], [Portable], [openssh-unix-dev@mindrot.org])
+AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_SRCDIR([ssh.c])
 AC_LANG([C])