Use "-V" for alex version check for better backward compatibility

Fixes #24302.
In recent versions of alex, "-v" is used for "--verbose" instead of "-version".

m4/fptools_alex.m4

@@ -14,7 +14,7 @@ AC_SUBST(AlexCmd,$ALEX)
 AC_CACHE_CHECK([for version of alex], fptools_cv_alex_version,
 changequote(, )dnl
 [if test x"$AlexCmd" != x; then
-   fptools_cv_alex_version=`"$AlexCmd" -v |
+   fptools_cv_alex_version=`"$AlexCmd" -V |
               grep 'Alex [Vv]ersion' | sed -e 's/Alex [Vv]ersion \([0-9\.]*\).*/\1/g'` ;
 else
    fptools_cv_alex_version="";