Add -lrapidcheck to pkg-config module

[roberth]

This adds the library to rapidcheck.pc, so that it doesn't have to be specified manually in projects that consume it.

The other modules don't need it because they have rapidcheck in their Requires: field.

I've tested this by temporarily patching the rapidcheck Nix package, and it behaves as expected.

[Ericson2314]

https://github.com/emil-e/rapidcheck/pull/319/files#r1438905129 oh oops see this thread. I think it's just missing the -L${libdir}?.

[Ericson2314]

Suggested change

	set(PKG_CONFIG_LIBS "-lrapidcheck")
	set(PKG_CONFIG_LIBS "-L\${libdir} -lrapidcheck")

[Ericson2314]

Per https://github.com/emil-e/rapidcheck/pull/319/files#r1523528740

[roberth]

It did not appear necessary, and isn't this redundant with set(PKG_CONFIG_LIBDIR "\${prefix}/lib") above?
Also should that line be set(PKG_CONFIG_LIBDIR "\${libdir}") then?

[Ericson2314]

It did not appear necessary,

I think that is because Nixpkgs adds all the -L flags. (BTW I think we should split out that part of the CC wrapper hook, so packages can opt to relying on proper pkg-configs a bit harder.)

and isn't this redundant with set(PKG_CONFIG_LIBDIR "\${prefix}/lib") above?

No because I think that is for defining libdir=....

Also should that line be set(PKG_CONFIG_LIBDIR "\${libdir}") then?

Then we could get the impredicative

libdir=${libdir}

What we want to end up with is

Libs: -L${libdir} -lrapidcheck

[roberth]

Nixpkgs adds all the -L flags.

Makes sense, so I've applied your suggestion.

No because I think that is for defining libdir=....

Ah, of course. I didn't see through the indirection and I thought this referred to some implicit CMake variables. It doesn't, and that's pretty obvious from the .pc contents.

Thanks!