pkg/41425: databases/db4/buildlink3.mk kills USE_LANGUAGES+=fortran

[cheusov%tut.by@localhost]

>Number:         41425
>Category:       pkg
>Synopsis:       databases/db4/buildlink3.mk kills USE_LANGUAGES+=fortran
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed May 13 20:45:00 +0000 2009
>Originator:     cheusov%tut.by@localhost
>Release:        NetBSD 5.0_STABLE
>Organization:
>Environment:
System: NetBSD chen.chizhovka.net 5.0_STABLE NetBSD 5.0_STABLE (GENERIC) #5: 
Fri May 1 16:04:32 EEST 2009 
cheusov%chen.chizhovka.net@localhost:/srv/obj/sys/arch/i386/compile/GENERIC i386
Architecture: i386
Machine: i386
>Description:
Under Linux several fortran-based packages fail.
One example is here:
http://mova.org/~cheusov/pub/pkgsrc-distbb/Linux/current/logs/20090426.0946/parallel_mpi-ch_mpich2-1.0.8nb1/stage_configure.html

"bmake configure" stage ends like this.

   => Linking db4 files into /tmp/obj_pkgsrc/parallel/mpi-ch/work/.buildlink.
   => Linking f2c files into /tmp/obj_pkgsrc/parallel/mpi-ch/work/.buildlink.
   ERROR: f2c>=20001205nb3 is not installed; can't buildlink files.
   *** Error code 1

This happens because f2c was not installed at "bmake depends" stage.
Package itself looks good. It adds fortran to USE_LANGUAGES and
normally it should work but does not under Linux and some other
!NetBSD platforms too. Why?

   0 mpi-ch>bmake show-var VARNAME=_ALL_DEPENDS
     digest>=20010302:../../pkgtools/digest tnftp-[0-9]*:../../net/tnftp \
     kbproto>=1.0.2:../../x11/kbproto xproto>=7.0.9:../../x11/xproto \
     perl>=5.0:../../lang/perl5  python25>=2.5.1:../../lang/python25 \
     python25>=2.5:../../lang/python25 libX11>=1.1:../../x11/libX11 \
     python25>=2.5.2:../../lang/python25 libX11>=0.99:../../x11/libX11
   0 mpi-ch>

Normally f2c>=20001205nb8:../../lang/f2c should appear in this output
but it doesn't.

The direct reason of this is that databases/db4/buildlink3.mk is
included to package's Makefile under Linux through
mk/bdb.buildlink3.mk <- lang/python25/buildlink3.mk <-
lang/python/pyversion.mk <- lang/python/application.mk

I didn't investigate the problem deeper but it looks like
something inside databases/db4/buildlink3.mk
somehow breaks USE_LANGUAGES settings.
>How-To-Repeat:
You can reproduce the problem under NetBSD by setting
BDB_ACCEPTED to db4.

>Fix:

Unknown