manager: add manager_set_unit_defaults() call that sets all unit defaults in one go

No change in behaviour. Just some refactoring.

src/basic/rlimit-util.h

@@ -4,6 +4,7 @@
 #include <sys/resource.h>
 
 #include "macro.h"
+#include "missing_resource.h"
 
 const char *rlimit_to_string(int i) _const_;
 int rlimit_from_string(const char *s) _pure_;
@@ -17,6 +18,7 @@ int rlimit_parse(int resource, const char *val, struct rlimit *ret);
 
 int rlimit_format(const struct rlimit *rl, char **ret);
 
+int rlimit_copy_all(struct rlimit* target[static _RLIMIT_MAX], struct rlimit* const source[static _RLIMIT_MAX]);
 void rlimit_free_all(struct rlimit **rl);
 
 #define RLIMIT_MAKE_CONST(lim) ((struct rlimit) { lim, lim })