tree-wide: use new RET_NERRNO() helper at various places

src/basic/mkdir.c

@@ -80,15 +80,11 @@ int mkdir_safe_internal(
 }
 
 int mkdir_errno_wrapper(const char *pathname, mode_t mode) {
-        if (mkdir(pathname, mode) < 0)
-                return -errno;
-        return 0;
+        return RET_NERRNO(mkdir(pathname, mode));
 }
 
 int mkdirat_errno_wrapper(int dirfd, const char *pathname, mode_t mode) {
-        if (mkdirat(dirfd, pathname, mode) < 0)
-                return -errno;
-        return 0;
+        return RET_NERRNO(mkdirat(dirfd, pathname, mode));
 }
 
 int mkdir_safe(const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags) {