Handles several --enable-gcc-warnings.

Handles several --enable-gcc-warnings.

* src/getargs.c (command_line_location): Set parameters to void.
* src/output.c (symbol_type_name_cmp): Make static.
(symbols_by_type_name): Set parameters to void.
(symbol_definitions_output): Remove unused parameter.  Rename as...
(prepare_symbol_definitions): this.
(muscles_output): Move symbol_definitions_output to...
(output): here as prepare_symbol_definitions.
* tests/c++.at (AT_CHECK_VARIANTS): Remove unused parameters of main.
(AT_CHECK_NAMESPACE): Make unused parameter lloc unnamed.