autoconf: Add configure target to main Makefile

While at it fill git version information in configure.ac
configure target needs autoconf, of course.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/INSTALL b/INSTALL
index ba9778c..fa9bf74 100644
--- a/INSTALL
+++ b/INSTALL
@@ -16,7 +16,7 @@
 Alternatively you can use autoconf generated ./configure script to
 set up install paths (via config.mak.autogen), so you can write instead
 
-	$ autoconf ;# as yourself if ./configure doesn't exist yet
+	$ make configure ;# as yourself
 	$ ./configure --prefix=/usr ;# as yourself
 	$ make all doc ;# as yourself
 	# make install install-doc ;# as root