Add missing semicolons.
Add a comment explaining a bunch of targets without any action lines.

idea why, but that was definitely wrong...

Make sure test doesn't barf because of missing spaces before the
closing ].
Add -lc to the list of libraries we depend upon.  Not always
necessary, but never hurts.

wrong, and my test engine doesn't show it.  The verbosity will be
temporary for about a day.

shared library, set those flags conditionally.

at all, and in all other cases, make sure foo.so is linked to
foo.so.{soversion}.

Add a variant of SHLIB_SOVER without the preceding period.

the version in the file name.

helper makefile that generalises our way of building shared libraries
and is designed to take care of almost anything (I hope).