xscale: Move debug handler to contrib/loaders

Avoid special rules to generate array at compile time by shipping
the generated file. Convert to Makefile build like the other
loaders.

Change-Id: I5a05edddcfaff3d395086cd3aa33120f8a7aa9dc
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/3864


Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>