Make the primary PQ_ macros available to modules by creating the pageq

Make the primary PQ_ macros available to modules by creating the pageq
array based on the maximum cache size instead of the selected cache
size.   Remove obsolete PQ_ options (leaving only PQ_CACHESIZE).

Move the vm_page_list_find() inline out of vm_page.h and into vm_page.c,
and provide an external function for other modules that use it.

Remove the 'disable page coloring' option (that nobody has ever used),
and related conditionals.  Page coloring never hurts and is now always on
to some degree.

Suggested-by: Hiten Pandya <hmp@backplane.com>
Agreed-with: Alan Cox <alc@cs.rice.edu>