read_goto_binary does not set the config

Fixes #2949

This enables auto-detecting the architecture of a goto-binary when
performing transformations on it, e.g., with main.c:

int main(){
  char buffer[] = "a";
  int x = strlen(buffer);
  return x;
}

the commands

  goto-cc -m32 -o main.gb main.c
  goto-instrument --add-library main.gb main2.gb

now pass.

Author: Daniel Kroening

src/goto-instrument/goto_instrument_parse_options.cpp

@@ -898,14 +898,16 @@ void goto_instrument_parse_optionst::get_goto_program()
 {
   status() << "Reading GOTO program from `" << cmdline.args[0] << "'" << eom;
 
+  config.set(cmdline);
+
   auto result = read_goto_binary(cmdline.args[0], get_message_handler());
 
   if(!result.has_value())
     throw 0;
 
   goto_model = std::move(result.value());
 
-  config.set(cmdline);
+  config.set_from_symbol_table(goto_model.symbol_table);
 }
 
 void goto_instrument_parse_optionst::instrument_goto_program()