scripts/gdb: add constants.py to .gitignore

Since scripts/gdb/linux/constants.py is autogenerated, this should have
been added to .gitignore when it was introduced.

Fixes: f197d75fcad1 ("scripts/gdb: provide linux constants")
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Omar Sandoval <[e-mail]>
Signed-off-by: Kieran Bingham <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

scripts/gdb/linux/.gitignore

···
 *.pyc
 *.pyo
+constants.py