Sort libraries by version and pick the shortest symlink (thanks @jpalus!)

Fixes https://github.com/libsdl-org/SDL_image/issues/289

configure.ac

@@ -58,6 +58,7 @@ dnl Detect the canonical build and host environments
 dnl AC_CANONICAL_HOST
 
 dnl Check for tools
+AC_PROG_AWK
 AC_PROG_CC
 AC_PROG_CXX
 AC_PROG_EGREP
@@ -65,6 +66,10 @@ AC_PROG_INSTALL
 AC_PROG_MAKE_SET
 PKG_PROG_PKG_CONFIG
 
+if [ test -z "$AWK" ]; then
+    AC_MSG_ERROR([*** awk not found, aborting])
+fi
+
 dnl 64-bit file offsets if possible unless --disable-largefile is specified
 AC_SYS_LARGEFILE
 
@@ -181,15 +186,7 @@ find_lib()
         host_lib_path="/usr/$base_libdir /usr/local/$base_libdir"
     fi
     for path in $env_lib_path $gcc_bin_path $gcc_lib_path $host_lib_path; do
-        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
-        fi
-    done
-    # Try again, this time allowing more than one version digit after the .so
-    for path in $env_lib_path $gcc_bin_path $gcc_lib_path $host_lib_path; do
-        lib=[`ls -- $path/$1 2>/dev/null | sed -e 's,.*/,,' | sort | tail -1`]
+        lib=[`ls -- $path/$1 2>/dev/null | sed 's,.*/,,' | sort -V -r | $AWK 'BEGIN{FS="."}{ print NF, $0 }' | sort -n -s | sed 's,[0-9]* ,,' | head -1`]
         if test x$lib != x; then
             echo $lib
             return