./configure gets it wrong when libunistring version is exactly 1.2.0

[Gordon Steemson]

I am attempting to build wget 1.24.5 from the source tarball, and discovered 
that `make test` fails to build.  A very long investigation revealed that a 
needed function, uc_width, is not getting compiled into gnulib:  it is defined 
in `lib/uniwidth/width.c`, which theoretically gets compiled into 
`libgnu-wcwidth.o`, but that never happens because my libunistring's version 
(1.2.0) triggers the configure script to comment that build instruction out of 
the Makefile (see the areas around line 62720 in `./configure` and around line 
390 in `./lib/Makefile`).  I am assuming this to be done by some obscure M4 
macro (perhaps one that came with Gnulib?), because libunistring is not 
referenced at all in `configure.ac`.

I'm going to work around it by either editing the Makefile or installing a 
newer version of libunistring, but this seemed like something you ought to be 
told about.

Gordon Steemson