Plan:
(1) Change USE_PERL5=build into USE_TOOLS+=perl.
(2) Change all other USE_PERL5 into including perl5/buildlink3.mk.
Possibly, for packages that don't actually build anything with perl,
but merely require it for the perl interpreter, we can instead do:
USE_TOOLS+= perl
TOOLS_DEPMETHOD.perl= DEPENDS
but this is more verbose than simply including the perl5/buildlink3.mk
file.
Move the PERL5_REQD computation into a lang/perl5/version.mk file,
and only do the USE_PERL5 logic in bsd.pkg.use.mk if we're not using
the new tools framework. This consolidates all of the perl-handling
into two places -- lang/perl5 and mk/tools/perl.mk.
in mk/tools/perl.mk since many packages expect to be able to use the
variables defined in vars.mk, but those variables can only be defined
if PERL5 is correctly defined, and that is only true after it is set
here.
the "TOOL" variables won't be properly defined for the top-leve make
after returning from making the install-depends target if we're using
the pkgsrc-supplied tool. Define the "TOOL" variable unconditionally
instead.
