tmpfiles: deal with kernel errno change if quota is not enabled

Old kernels returned EINVAL if quota was off but we tried to manipulate
it anyway. Since
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8a36e408d40606e21cd4e2dd9601004a67b14868
this changed: now ENOTCONN is returned. This of course is a kernel API
compat breakage, but let's not make a fuss and just map EINVAL to
ENOTCONN to make it recognizable the same way everywhere.

Fixes: #15896

src/basic/btrfs-util.c

@@ -927,9 +927,12 @@ static int qgroup_create_or_destroy(int fd, bool b, uint64_t qgroupid) {
         for (c = 0;; c++) {
                 if (ioctl(fd, BTRFS_IOC_QGROUP_CREATE, &args) < 0) {
 
-                        /* If quota is not enabled, we get EINVAL. Turn this into a recognizable error */
-                        if (errno == EINVAL)
-                                return -ENOPROTOOPT;
+                        /* On old kernels if quota is not enabled, we get EINVAL. On newer kernels we get
+                         * ENOTCONN. Let's always convert this to ENOTCONN to make this recognizable
+                         * everywhere the same way. */
+
+                        if (IN_SET(errno, EINVAL, ENOTCONN))
+                                return -ENOTCONN;
 
                         if (errno == EBUSY && c < 10) {
                                 (void) btrfs_quota_scan_wait(fd);