When r207410 eliminated the acquisition and release of the page queues

When r207410 eliminated the acquisition and release of the page queues
lock from pmap_extract_and_hold(), it didn't take into account that
pmap_pte_quick() sometimes requires the page queues lock to be held.
This change reimplements pmap_extract_and_hold() such that it no
longer uses pmap_pte_quick(), and thus never requires the page queues
lock.

For consistency, adopt the same idiom as used by the new
implementation of pmap_extract_and_hold() in pmap_extract() and
pmap_mincore().  It also happens to make these functions shorter.

Fix a style error in pmap_pte().

Reviewed by:	kib@