Support for "special" libraries

One that as a build system implementor I have to deal with often, is pkg-config files with dependencies on "special" libraries. Whether this is `libdl` or `libm`, which are part of libc on some implementations (or versions of implementations) or separate libraries on others; to things like OpenGL, which are part of the base OS in Windows and MacOS, or provide standard lookup mechanisms on Linux and Unicies; to systems like OpenMP which are part of the compiler implementation, but can still be useful to abstract as a dependency since they are not part of the language standard, but an additional feature that some compilers implement (some versions of), and there may be specific requirements for (such as, I require OpenMP of at least version 3.2 to function).

It would be nice to avoid having to do what is currently done in for pkg-config with these libaries (or flags) and just shove them into the cflags/libs lines and hope for the best.

I don't have a vision of how this would work, but maybe others have ideas?