By using the command "add_help_text" to add a help text to a TCL
procedure it implicitly creates a new command_registration struct
that has field .usage set to NULL. This triggers a debug message
BUG: command '%s' does not have the '.usage' field filled out
Use an empty string if usage field is NULL.
Plus, do not annoy the user with a LOG_INFO when the command
"add_usage_text" replaces an empty usage.
Change-Id: I4a72646e0fb704ba354f938d774055540cde3967
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5025
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
c19de41a0f