#2751: disourage --enable-shared in ./configure --help

configure.ac

@@ -725,7 +725,7 @@ dnl ** Build shared and/or static libs?
 dnl --------------------------------------------------------------
 AC_ARG_ENABLE(shared,
 [AC_HELP_STRING([--enable-shared],
-[Build shared libraries, if available. [default=no]])],
+[Build shared libraries, if available (EXPERIMENTAL, non-working). [default=no]])],
 [ if test x"$enableval" = x"yes"; then
         AC_MSG_WARN([--enable-shared is experimental and not fully supported at this time])
         BuildSharedLibs=YES