Revert "gdb: disable loading of auto-loaded files"

This reverts commit 77a270a948216a8bb5bcc960042aeb467794b593.

Turning auto-load off also turns the pretty printer off.

Unfortunately, we must trust to providers of the auto-loaded scripts.
(Jakub Filak must start fixing root causes and stop treating symptoms.)

Signed-off-by: Jakub Filak <jfilak@redhat.com>