cvs commit: src/lib/msun/i387 fenv.c fenv.h

[Warner Losh]

> What's the problem with ports? I think one who want to run older ports 
> on newer system can install compatXX package, no?

The problem is that we encode the major number of the library into the
shared libraries that we produce.  This leads to situations where
you've installed binaries from both releases that can cause a program
to need to bring in libc.so.4 and libc.so.5, which is fatal.

In order to avoid this, one must never bump libc's major number, or
one must always bump all the libraries that depend on it.  We're not
doing either, and that creates binary incompatibility.

Warner