bug#55294: Configure failure on Solaris 11.4

[Eli Zaretskii]

> Cc: 55294@debbugs.gnu.org
> From: Steve Downey <sdowney@gmail.com>
> Date: Mon, 9 May 2022 20:15:56 -0400
> 
> In 11.4, sqrt is defined in libc.so as an absolute symbol, so the test for if 
> -lm is necessary succeeds without
> it. I haven't disassembled the new libc, but I suspect that you're right and 
> they have a sqrt that is fast enough
> either depends on a sqrt instruction or is otherwise "simple" for some value 
> of simple. 

So you are saying that sqrt was actually in libc, but the rest of math
functions are in libm, is that right?

If so, perhaps to make this test more future-proof, we should try
several functions, not just one?