Check that BASERUBY is at least Ruby 2.2 in configure

BASERUBY needs to be at least Ruby 2.2 since
46acd00.

I think it's better to explicitly fail early as soon as BASERUBY
is used in this case, versus trying to debug later failures.

This modifies things to check both implicitly use of ruby in the
PATH as BASERUBY, and explicitly specified older versions of ruby
when using --with-baseruby.

Fixes [Bug #16668]

configure.ac

@@ -34,7 +34,7 @@ AC_ARG_WITH(baseruby,
 	[
 		AC_PATH_PROG([BASERUBY], [ruby], [false])
 	])
-AS_IF([test "$HAVE_BASERUBY" = yes -a "`RUBYOPT=- $BASERUBY --disable=gems -e 'print 42' 2>/dev/null`" = 42], [
+AS_IF([test "$HAVE_BASERUBY" != no -a "`RUBYOPT=- $BASERUBY --disable=gems -e 'print 42 if RUBY_VERSION > "2.2"' 2>/dev/null`" = 42], [
     BASERUBY="$BASERUBY --disable=gems"
     BASERUBY_VERSION=`$BASERUBY -v`
     $BASERUBY -C "$srcdir" tool/downloader.rb -d tool -e gnu config.guess config.sub >&AS_MESSAGE_FD