shared libraries, when to use them

[Guy Harris]

> 4.) If you need to support multiple versions of an OS and don't want
>     to have to worry about what version of the shared libraries your
>     users have.

Depends on the multiple versions in question.  In some cases, linking on
the older system should suffice (modulo bugs, but kernel bugs can trip
up binaries built on other system, as well; in some sense, "/*ix*" can
be thought of as a shared library, and I think it *is* one in AIX 3.x).

E.g., if you have both 4.0.3 and 4.1[.x] systems, build on the 4.0.3
system.  (I'm told one vendor keeps a 4.0 - not 4.0.x, *4.0* - system
around for building its products.)