If a NULL pointer is passed, don't attempt to increment it. This avoids
passing the now not-NULL pointer on and eventually segfaulting. Also
remove some unnecessary temporary variables.
Change-Id: I268e225121aa283d59179bfae407ebf6959d3a4e
Signed-off-by: Darius Rad <darius@bluespec.com>
Reviewed-on: http://openocd.zylin.com/4550
Tested-by: jenkins
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>