Create "bin" directory so that zloop.sh works

Before running zloop.sh, we need to run `scripts/zfs-tests.sh -c` to
create and populate the `bin` directory with symlinks to our utilities.
Rather than making developers remember to do this, `make` should do it
for them.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #7525 
Closes #7547

Makefile.am

@@ -37,6 +37,9 @@ distclean-local::
 		-o -name '*.gcno' \) \
 		-type f -print | xargs $(RM)
 
+all-local:
+	-${top_srcdir}/scripts/zfs-tests.sh -c
+
 dist-hook:
 	sed -i 's/Release:[[:print:]]*/Release:      $(RELEASE)/' \
 		$(distdir)/META