and a package that is looking for zlib.pc won't find it anyway.
Why wouldn't it? `pkg-config zlib --cflags/--libs'.
Because built-in zlib (the one that comes with an operating system, like NetBSD
or Darwin aka Mac OS X) does not come with zlib.pc.
% pkg-config zlib --cflags
Package zlib was not found in the pkg-config search path.
Perhaps you should add the directory containing `zlib.pc'
to the PKG_CONFIG_PATH environment variable
No package 'zlib' found
Therefore, I don't see much point of adding zlib.pc to the package. Or am I
wrong?
Yes. I've already tested a case where a package uses zlib.pc and am waiting
for the commits to devel/zlib to push the changes into pkgsrc-wip.
That would force all packages that expect zlib.pc to be build with pkgsrc zlib,
rather than using system-provided one.