package/gdb: don't remove support files if python chosen

package/gdb: don't remove support files if python chosen

If one wants to use GDB with python support on the target, you need the support
files installed by GDB. These get usually deleted to save some space, so I just
wrapped the Makefile code deleting them in a conditional block depending on if
python support is active or not.

Signed-off-by: Jonas Zaddach <jzaddach@cisco.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
[Thomas:
 - use positive logic "if python is disabled"
 - put the comment inside the condition, as suggested by Arnout]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>