journald: remove unconditional log_*() use in the main loop

Setting MaxRetentionSec= caused the kernel log to overflow and the
journal daemon to enter an endless loop.

Logging from the journald main loop gets directed to /dev/kmsg,
which wakes up journald again. We skip the import of this message
by checking for our own PID, but this still causes the main loop
to never go to sleep again because we never stopped logging from
there.

TODO

@@ -1,14 +1,4 @@
 Bugfixes:
-* journal: setting MaxRetentionSec= to any value creates a /dev/kmsg loop:
-    epoll_wait(7, {?} 0x7fff220df200, 1, 799489421) = 1
-    read(8, "46,156226155,545165984,-;systemd"..., 8192) = 75
-    writev(6, [{"<46>", 4}, {"systemd-journald", 16}, {"[3822]: ", 8}, {"Sleeping for 799489421 ms", 25}, {"\n", 1}], 5) = 54
-    epoll_wait(7, {?} 0x7fff220df200, 1, 799489421) = 1
-    read(8, "46,156226156,545166076,-;systemd"..., 8192) = 75
-    writev(6, [{"<46>", 4}, {"systemd-journald", 16}, {"[3822]: ", 8}, {"Sleeping for 799489421 ms", 25}, {"\n", 1}], 5) = 54
-    epoll_wait(7, {?} 0x7fff220df200, 1, 799489421) = 1
-    https://bbs.archlinux.org/viewtopic.php?pid=1200373
-
 * check systemd-tmpfiles for selinux context hookup for mknod(), symlink() and similar
 
 * swap units that are activated by one name but shown in the kernel under another are semi-broken

src/journal/journald.c

@@ -88,7 +88,6 @@ int main(int argc, char *argv[]) {
 
                         /* Calculate when to rotate the next time */
                         t = (int) ((server.oldest_file_usec + server.max_retention_usec - n + USEC_PER_MSEC - 1) / USEC_PER_MSEC);
-                        log_info("Sleeping for %i ms", t);
                 }
 
 #ifdef HAVE_GCRYPT