Handle conflicts of function name and argument name

[yutannihilation]

#[savvy]
pub fn args(args: ListSexp) -> savvy::Result<savvy::Sexp> {
  ...
}

SEXP args__impl(SEXP args) {
    SEXP res = args(args);
    return handle_result(res);
}

init.c: In function 'args__impl':
init.c:186:16: error: called object 'args' is not a function or function pointer
  186 |     SEXP res = args(args);
      |                ^~~~
init.c:185:22: note: declared here
  185 | SEXP args__impl(SEXP args) {
      |                 ~~~~~^~~~
make: *** [C:/PROGRA~1/R/R-devel/etc/x64/Makeconf:282: init.o] Error 1
ERROR: compilation failed for package 'savvyExamples'