proc-cmdline: make proc_cmdline_get_bool() take flags

All other command line parsers takes flags. Let's make
proc_cmdline_get_bool() also take flags. Though, currently,
no flag is set by the caller.

src/shared/cgroup-setup.c

@@ -96,7 +96,7 @@ bool cg_is_unified_wanted(void) {
                 return (wanted = r >= CGROUP_UNIFIED_ALL);
 
         /* If we were explicitly passed systemd.unified_cgroup_hierarchy, respect that. */
-        r = proc_cmdline_get_bool("systemd.unified_cgroup_hierarchy", &b);
+        r = proc_cmdline_get_bool("systemd.unified_cgroup_hierarchy", /* flags = */ 0, &b);
         if (r > 0)
                 return (wanted = b);
 
@@ -147,7 +147,7 @@ bool cg_is_hybrid_wanted(void) {
 
         /* Otherwise, let's see what the kernel command line has to say.  Since checking is expensive, cache
          * a non-error result. */
-        r = proc_cmdline_get_bool("systemd.legacy_systemd_cgroup_controller", &b);
+        r = proc_cmdline_get_bool("systemd.legacy_systemd_cgroup_controller", /* flags = */ 0, &b);
 
         /* The meaning of the kernel option is reversed wrt. to the return value of this function, hence the
          * negation. */

src/shared/condition.c

@@ -748,7 +748,7 @@ static int condition_test_needs_update(Condition *c, char **env) {
         assert(c->parameter);
         assert(c->type == CONDITION_NEEDS_UPDATE);
 
-        r = proc_cmdline_get_bool("systemd.condition-needs-update", &b);
+        r = proc_cmdline_get_bool("systemd.condition-needs-update", /* flags = */ 0, &b);
         if (r < 0)
                 log_debug_errno(r, "Failed to parse systemd.condition-needs-update= kernel command line argument, ignoring: %m");
         if (r > 0)

src/shared/reboot-util.c

@@ -113,7 +113,7 @@ int shall_restore_state(void) {
         bool ret;
         int r;
 
-        r = proc_cmdline_get_bool("systemd.restore_state", &ret);
+        r = proc_cmdline_get_bool("systemd.restore_state", /* flags = */ 0, &ret);
         if (r < 0)
                 return r;