How to best check a configuration of another port/package?

[Gerald Pfeifer]

In https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=237688 we had
a user report against lang/gcc* ports that could be traced back to
a certain functionality (option) in another port (devel/binutils)
missing.

In pseudo-code this could be addressed as follows in lang/gcc* 

   .if $(binutils built statically)
   IGNORE= GCC requires dynamically linked binutils
   .endif

Now the question is: How to implement something like this practically?

Gerald @FreeBSD.org