--libs-only-L The -L/-R stuff
--libs-only-l The -l stuff
--static Output ilbraries suitable for static linking
and then says the union of -only-L and -only-l may be smaller than the
output of -libs because the latter might include flags like -rdynamic.
We're already having to parse the output of pkg-config to try and
separate LDADD stuff from LDFLAGS stuff, And this is before we start to
address static v. dynamic things.
This is because we really don't want -L stuff in LDADD, because we end
up with things like:
No rule to make: -L /usr/local/lib
(or something).