Restore -dev suffix

Change-Id: I3662c5993766a76d6dd62b919c56cc059c4e50d4
Signed-off-by: Freddie Chopin <freddie.chopin@gmail.com>

configure.ac

 AC_PREREQ(2.60)
-AC_INIT([openocd], [0.7.0-rc1],
+AC_INIT([openocd], [0.7.0-rc1-dev],
   [OpenOCD Mailing List <openocd-devel@lists.sourceforge.net>])
 AC_CONFIG_SRCDIR([src/openocd.c])