Fix ruby test to handle 1.8 ruby installations.

config/interface.rb

 require 'mkmf'
 if RUBY_VERSION[0,3] == '1.8'
-  puts "-I#{Config::expand(CONFIG['rubyhdrdir'])}"
+  puts "-I#{Config::expand(CONFIG['archdir'])}"
 else
   puts "-I#{Config::expand(CONFIG['rubyhdrdir'])} -I#{Config::expand(CONFIG['rubyhdrdir'])}/#{Config::expand(CONFIG['arch'])}"
 end

configure

@@ -26250,7 +26250,7 @@ $as_echo "no" >&6; }
 fi
-   RUBY_INCLUDES="$($RUBY config/interface.rb)"
+   RUBY_INCLUDES="$($RUBY $srcdir/config/interface.rb)"
    save_CPPFLAGS=$CPPFLAGS
    CPPFLAGS="$CPPFLAGS $RUBY_INCLUDES"
    ac_fn_c_check_header_mongrel "$LINENO" "ruby.h" "ac_cv_header_ruby_h" "$ac_includes_default"
@@ -26297,7 +26297,7 @@ else
 fi
 #  ----------------------------------------------------------------------
-#  Create the Ruby Interface via swig
+#  Create the Python Interface via swig
 # Check whether --enable-python was given.
 if test "${enable_python+set}" = set; then :
   enableval=$enable_python; # Extract the first word of "python", so it can be a program name with args.

configure.ac

@@ -123,7 +123,7 @@ AM_CONDITIONAL(ENABLE_SWIG,[test "x$SWIG" != "x"])
 AC_ARG_ENABLE(ruby,
   [AS_HELP_STRING([--enable-ruby],[ruby language bindings [default=no] (EXPERIMENTAL)])],
   [AC_CHECK_PROG(RUBY,ruby,ruby)
-   RUBY_INCLUDES="$($RUBY config/interface.rb)"
+   RUBY_INCLUDES="$($RUBY $srcdir/config/interface.rb)"
    save_CPPFLAGS=$CPPFLAGS
    CPPFLAGS="$CPPFLAGS $RUBY_INCLUDES"
    AC_CHECK_HEADER([ruby.h],,[enable_ruby=no