compilation errors on Ruby 1.9

[Sandra]

STR2CSTR() and RSTRING()->len have been removed from Ruby 1.9 (see the Ruby ChangeLog entry on Sat Jan 31 22:29:05 2009 by Tanaka Akira), so lines 38 and 39 of interface/ruby/libdrizzle.i should be updated to

  $1 = StringValuePtr($input);
  $2 = (size_t)RSTRING_LEN($input);