Logging API allows for trivial segfaulting usage

[jnpkrn]

git apply <<EOF
diff --git a/examples/simplelog.c b/examples/simplelog.c
index eec0053..33c5f7b 100644
--- a/examples/simplelog.c
+++ b/examples/simplelog.c
@@ -210,7 +210,7 @@ main(int32_t argc, char *argv[])
 		qb_log_filter_ctl(QB_LOG_BLACKBOX, QB_LOG_FILTER_ADD,
 				  QB_LOG_FILTER_FILE, "*", LOG_DEBUG);
 		qb_log_ctl(QB_LOG_BLACKBOX, QB_LOG_CONF_SIZE, 4096);
-		qb_log_ctl(QB_LOG_BLACKBOX, QB_LOG_CONF_THREADED, QB_FALSE);
+		qb_log_ctl(QB_LOG_BLACKBOX, QB_LOG_CONF_THREADED, do_threaded);
 		qb_log_ctl(QB_LOG_BLACKBOX, QB_LOG_CONF_ENABLED, QB_TRUE);
 	}
 	if (logfile) {
@@ -247,7 +247,7 @@ main(int32_t argc, char *argv[])
 		qb_log(LOG_ERR, "no syslog");
 	}
 
-	if (do_blackbox) {
+	if (do_blackbox && 0) {
 		logfile = NULL;
 		logfile[5] = 'a';
 	} else {
EOF
make simplelog
./simplelog -bt

resulting in

Ringbuffer: 
 ->OVERWRITE
 ->write_pt [0]
 ->read_pt [0]
 ->size [2048 words]
 =>free [8192 bytes]
 =>used [0 bytes]
Segmentation fault (core dumped)

(No, this time it's not intended case that's currently neutralized.)

It depends on further investigation how much thread-safe ringbuffer implementation actually is.