Add log_vprintf_lf() to enable the possibility to output log messages
with a variable argument list.
Change-Id: I7fd6e93db63a7d98f662df2881a42e4d923c3848
Signed-off-by: Marc Schink <openocd-dev@marcschink.de>
Reviewed-on: http://openocd.zylin.com/3709
Tested-by: jenkins
Reviewed-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Paul Fertser <fercerpav@gmail.com>