Improved find_lib, gets the latest version of libpng, etc.

configure.in

@@ -119,7 +119,7 @@ find_lib()
         host_lib_path="/usr/$base_libdir /usr/local/$base_libdir"
     fi
     for path in $gcc_bin_path $gcc_lib_path $env_lib_path $host_lib_path; do
-        lib=[`ls -- $path/$1 2>/dev/null | sort | sed 's/.*\/\(.*\)/\1/; q'`]
+        lib=[`ls -- $path/$1 2>/dev/null | sed -e '/\.so\..*\./d' -e 's,.*/,,' | sort | tail -1`]
         if test x$lib != x; then
             echo $lib
             return