Disable Go (6g/8g) if the version is too old.

git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk@12323 626c5289-ae23-0410-ae9c-e8d60b6d4f22

configure.in

@@ -2009,6 +2009,12 @@ else
     GOGCC=false
     if $GO --help 2>/dev/null | grep gccgo >/dev/null 2>&1 ; then
 	GOGCC=true
+    else
+	go_version=`$GO -V | sed -e 's/.*version \([[0-9]]*\).*/\1/'`
+	if test "$go_version" -lt 6707; then
+	    AC_MSG_NOTICE([Installed Go too old; disabling Go])
+	    GO=
+	fi
     fi
 
 fi