tools: add skeleton of kmod tool

If using libtool 2.4.2, running the script generated by libtool will not
work because libtool changes argv[0] to lt-progname.

To test this is necessary to either fix the installed
build-aux/ltmain.sh file or run the binary directly like in:

$ export LD_LIBRARY_PATH=$PWD/libkmod/.libs/
$ ./tools/.libs/kmod help
diff --git a/Makefile.am b/Makefile.am
index 6d598e3..3eaef81 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -82,13 +82,16 @@
 
 if BUILD_TOOLS
 bin_PROGRAMS = tools/kmod-insmod tools/kmod-rmmod tools/kmod-lsmod \
-	tools/kmod-modprobe tools/kmod-modinfo
+	tools/kmod-modprobe tools/kmod-modinfo tools/kmod
 
 tools_kmod_insmod_LDADD = libkmod/libkmod.la
 tools_kmod_rmmod_LDADD = libkmod/libkmod.la
 tools_kmod_lsmod_LDADD = libkmod/libkmod.la
 tools_kmod_modprobe_LDADD = libkmod/libkmod.la
 tools_kmod_modinfo_LDADD = libkmod/libkmod.la
+
+tools_kmod_SOURCES = tools/kmod.c tools/kmod.h
+tools_kmod_LDADD = libkmod/libkmod.la
 endif
 
 TESTS = test/test-init test/test-loaded