os-posix: remove confused errno

If we get inside the 'else if (status == 1)' conditional,
then we know that read() succeeded, and therefore errno is
unspecified. Printing strerror(errno) on a random value
is not helpful.

Cc: Eric Blake <eblake@redhat.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

os-posix.c

@@ -226,7 +226,7 @@ void os_daemonize(void)
                 exit(1);
             }
             else if (status == 1) {
-                fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno));
+                fprintf(stderr, "Could not acquire pidfile\n");
                 exit(1);
             } else {
                 exit(0);