shared/options: store argc+argv in the OptionParser state struct

After writing the code to parse options in a bunch of places, I think
passing the argc+argv to various functions to query state is annoying.
It seems nicer to just stash them in the state struct once.

src/validatefs/validatefs.c

@@ -62,10 +62,10 @@ static int parse_argv(int argc, char *argv[]) {
         assert(argc >= 0);
         assert(argv);
 
-        OptionParser state = {};
+        OptionParser state = { argc, argv };
         const char *arg;
 
-        FOREACH_OPTION(&state, c, argc, argv, &arg, /* on_error= */ return c)
+        FOREACH_OPTION(&state, c, &arg, /* on_error= */ return c)
                 switch (c) {
                 OPTION_COMMON_HELP:
                         return help();
@@ -88,7 +88,7 @@ static int parse_argv(int argc, char *argv[]) {
                         break;
                 }
 
-        char **args = option_parser_get_args(&state, argc, argv);
+        char **args = option_parser_get_args(&state);
 
         if (strv_length(args) != 1)
                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),