Reinstates 'bp_members_screen_display_profile' action for theme compat mode

This action hook, which is present in the legacy screen function, appears not
to have been included when the screen functions were migrated to theme compat.

Fixes #5001

Props mjustice

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7068 cdf35c40-ae34-48e0-9cc9-0c9da1808c22