Submitted by: hoek
(2) ELF support.
2a. Variable PORTOBJFORMAT specifies the object format of the system.
It is passed down to configure/make via CONFIGURE_ENV/MAKE_ENV,
and is given to generate-plist via PLIST_SUB.
2b. In PLIST, substitute lines that end with "/libFOO.so.X" with
"/libFOO.so.X.0". (This means PLISTs should only list ELF
libraries.)
Reviewed by: jb, jdp, hoek, jseger, steve
(3) Perl5-in-system support. Basically turns USE_PERL5 into a no-op
if there exists a "/usr/bin/perl5". Also fix prior breakage by
dima (${PREFIX} => ${LOCALBASE} in perl5 path).
Reviewed by: markm (sort of)
(4) Install requirement file as "+REQUIRE" so it will be executed
correctly by pkg_delete.
Reported by: Shigeyuki FUKUSHIMA <shige@kuis.kyoto-u.ac.jp>
(5) Do not disable checksum and makesum when NO_EXTRACT is set.
Pointed out by: hoek and kiri, among other people