How to check PKG_OPTIONS of a dependent package

[Jens Rehsack <rehsack%googlemail.com@localhost>]

Hi,

a few weeks ago I detected a problem with www/apache22: it installs 2
modules which are not in PLIST:
- lib/httpd/mod_authnz_ldap.so
- lib/httpd/mod_ldap.so
I talked with tron@ and he told me, that's because of I compiled apr (or
similar) with PKG_OPTIONS+=ldap (sounds reasonable and is true).

Because of I have a similar problem with the update of graphics/p5-GD:
On AIX it's required to include ../../x11/libXp/buildlink3.mk and
../../mk/xaw.buildlink3.mk when gd is compiled with PKG_OPTIONS+=x11. joerg@
told me, this could be an AIX problem because of their non-transitive linker
(I don't understand what he mean - I just quote him here).

But these problems result in my question: how can I check the PKG_OPTIONS of
a dependent package to change some local behaviour?

Thanks in advance,
Jens