tree-wide: extend verbs functions with extra per-verb data parameter

We often have a pattern where the same verb function is used for
multiple actions. This leads to an antipattern where we figure out what
action needs to be taken from argv[0] multiple times: often once in
parse_argv() to figure out what options are allowed, then once again
implicitly in dispatch_verb(), and then again in the action verb itself.
Let's allow passing a parameter into the verb to simplify this.

This matches a pattern we have in conf-parser.h, where we have both
void *userdata (more global) and void *data (per-config item). Here,
I opted for uintptr_t userdata. It seems that most of the time we'll
want to just pass an enum value. This works OK with no casts. I also
tried a void* and union. In both cases, much more boilerplate is needed:
either a cast or a macro to help avoid compiler warnings. uintptr_t
seems generic enough to cover foreseeable usecases with no fuss.

This is a noop refactoring. See next commit for an example.

src/hostname/hostnamectl.c

@@ -549,7 +549,7 @@ static int get_hostname_based_on_flag(sd_bus *bus) {
         return get_one_name(bus, attr, NULL);
 }
 
-static int verb_show_status(int argc, char **argv, void *userdata) {
+static int verb_show_status(int argc, char *argv[], uintptr_t _data, void *userdata) {
         sd_bus *bus = userdata;
         int r;
 
@@ -601,7 +601,7 @@ static int set_simple_string(sd_bus *bus, const char *target, const char *method
         return set_simple_string_internal(bus, NULL, target, method, value);
 }
 
-static int verb_set_hostname(int argc, char **argv, void *userdata) {
+static int verb_set_hostname(int argc, char *argv[], uintptr_t _data, void *userdata) {
         _cleanup_free_ char *h = NULL;
         const char *hostname = argv[1];
         sd_bus *bus = userdata;
@@ -687,27 +687,27 @@ static int verb_set_hostname(int argc, char **argv, void *userdata) {
         return ret;
 }
 
-static int verb_get_or_set_hostname(int argc, char **argv, void *userdata) {
+static int verb_get_or_set_hostname(int argc, char *argv[], uintptr_t data, void *userdata) {
         return argc == 1 ? get_hostname_based_on_flag(userdata) :
-                           verb_set_hostname(argc, argv, userdata);
+                           verb_set_hostname(argc, argv, data, userdata);
 }
 
-static int verb_get_or_set_icon_name(int argc, char **argv, void *userdata) {
+static int verb_get_or_set_icon_name(int argc, char *argv[], uintptr_t _data, void *userdata) {
         return argc == 1 ? get_one_name(userdata, "IconName", NULL) :
                            set_simple_string(userdata, "icon", "SetIconName", argv[1]);
 }
 
-static int verb_get_or_set_chassis(int argc, char **argv, void *userdata) {
+static int verb_get_or_set_chassis(int argc, char *argv[], uintptr_t _data, void *userdata) {
         return argc == 1 ? get_one_name(userdata, "Chassis", NULL) :
                            set_simple_string(userdata, "chassis", "SetChassis", argv[1]);
 }
 
-static int verb_get_or_set_deployment(int argc, char **argv, void *userdata) {
+static int verb_get_or_set_deployment(int argc, char *argv[], uintptr_t _data, void *userdata) {
         return argc == 1 ? get_one_name(userdata, "Deployment", NULL) :
                            set_simple_string(userdata, "deployment", "SetDeployment", argv[1]);
 }
 
-static int verb_get_or_set_location(int argc, char **argv, void *userdata) {
+static int verb_get_or_set_location(int argc, char *argv[], uintptr_t _data, void *userdata) {
         return argc == 1 ? get_one_name(userdata, "Location", NULL) :
                            set_simple_string(userdata, "location", "SetLocation", argv[1]);
 }
@@ -752,7 +752,7 @@ static int help(void) {
         return 0;
 }
 
-static int verb_help(int argc, char **argv, void *userdata) {
+static int verb_help(int argc, char *argv[], uintptr_t _data, void *userdata) {
         return help();
 }