Add reset_schedlock declaration in target.h.

Add reset_schedlock declaration in target.h.

This patches improves a couple of previous patches:
  - one that introduces reset_schedlock, but failed to add a declarationl;
  - one that was checked in to avoid a compilation failure due to that
    missing declaration.
It also improves the declaration itself to better conform to our coding
practices.  Same for the comments.

2010-05-17  Joel Brobecker  <brobecker@adacore.com>

        * target.h (reset_schedlock): Add declaration.
        * infrun.c (reset_schedlock): Add missing void in function profile.
        * target.c (target_mourn_inferior): Delete local declaration of
        reset_schedlock.  Style-fix in comment.