Fix C parser compiler warnings

[ydah]

The C parser currently declares and defines several no-argument functions using empty parameter lists:

void Init_graphql_c_parser_ext() {

In C, () leaves the parameters unspecified and GCC reports these definitions with -Wold-style-definition:

warning: old-style function definition [-Wold-style-definition]

The parser's yyerror function always raises through rb_exc_raise, but it is not declared as non-returning, which produces an additional compiler warning.

This PR updates the no-argument declarations and definitions to use (void) and marks yyerror with Ruby's portable NORETURN macro. The Ragel and Bison source files and their generated C files are updated together.

There is no runtime behavior change.

[rmosolgo]

Thanks!