the curl build system goes through a good amount of effort to try and figure out when some external libs need other external libs, often for static linking purposes. for example, it probes openssl and then tries to see if openssl also needs zlib and libdl. this doesn't always work (new libs get added and curl doesn't probe those, or the libs get rebuilt which means curl needs to be rebuilt simply to reprobe the library).

ideally the libcurl.pc file, instead of looking like:

Libs.private: -lnghttp2 -lssl -lcrypto -lssl -lcrypto -lz

it would look like:

Libs.private:
Requires.private: libnghttp2 openssl zlib

now (1) the data will always be up-to-date regardless of how those other libs were configure/rebuilt/updated, and (2) curl wouldn't have to do all that probing.

NB: (1) can be done now and generally w/out pain, but (2) would mean that curl's build system itself would now rely on pkg-config being available/sane at build time. not sure if non-pkg-config builds is something curl cares about.