pages that are installed will be gzip-compressed, if MANZ is set, or
not if MANZ is not set. If the package uses bsd-style .mk files, the
variable MANCOMPRESSED_IF_MANZ should be set to a value of "yes" in
the package Makefile. This replaces the previous method of specific
inclusion of bsd.prefs.mk, followed by a check for MANZ and
conditional assignment of MANCOMPRESSED.
Add appropriate documentation, and change all necessary ocurrences in
package Makefiles.
