Problems build a package with a shared library

[Marc Balmer <marc%msys.ch@localhost>]

I have a shared library for NetBSD that is build using a Makefile that
includes bsd.lib.mk.  The build directory has a shlib_version file.

When I build that library on NetBSD using make, I get libname.so,
libname.so.1, and libname.so.1.0.  .so and .so.1 are symlinks to .so.1.0.

Now I want to build this library as a pkgsrc package, but when I build
it under pkgsrc, the symlinks .so and so.1 are not created, although it
is using the same Makefile.

This looks like a newer regression (2013Q3 or so), as previous pkgsrc
releases did build everything as expected.

Any ideas?