Use cc instead of ld for creating shared libraries

[jkj]

Simple change to use ${CC} to created shared objects rather than using ld directly, so that the compiler driver has the opportunity to do things the way it wants them done.

[katef]

I think this will break for macos, because the other flags for LDFLAGS are written for ld, not cc. e.g.:

LDSFLAGS += -macosx_version_min ${MACOSX_VERSION_MIN}

for some cases gcc has an equivalent flag to pass those along (i.e. -mmacosx_version_min, with the extra m).

For -dylib -flat_namespace -undefined dynamic_lookup I haven't checked. Those could be passed along by -Wl,... but if we're calling ${CC} here I'd rather use gcc and clang's equivalent flags where they're provided.

[katef]

Let's call that LDS, because it matches LDSFLAGS below

[katef]

Don't forget to update the manpages too please!