Remove the source directory .num targets

Remove the source directory .num targets

$(SRCDIR)/util/libcrypto.num and $(SRCDIR)/util/libssl.num were made their
own targets to have 'make ordinals' reproduce them (run mknum.pl) only if
needed.

Unfortunately, because the shared library linker scripts depend on these
.num files, we suddenly have mknum.pl run at random times when building.
Furthermore, this created a diamond dependency, which disturbs parallell
building because multiple mknum.pl on the same file could run at the same
time.

This reverts commit 0e55c3ab8d702ffc897c9beb51d19b14b7896182.

Fixes #21999
Partially fixes #22841

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22890)