Fix use of getrandom() for Linux and WITH_TLS=no.

ChangeLog.txt

@@ -5,6 +5,10 @@ Broker:
 - Fix detection of incoming v3.1/v3.1.1 bridges. Closes #1263.
 - Fix default max_topic_alias listener config not being copied to the in-use
   listener when compiled without TLS support.
+- Fix random number generation if compiling using WITH_TLS=no and on Linux
+  with glibc >= 2.25. Without this fix, no random numbers would be generated
+  for e.g. on broker client id generation, and so clients connecting expecting
+  this feature would be unable to connect.
 
 Clients:
 - Fix -L url parsing when `/topic` part is missing.

lib/util_mosq.c

@@ -326,7 +326,7 @@ int util__random_bytes(void *bytes, int count)
 		rc = MOSQ_ERR_SUCCESS;
 	}
 #elif defined(__GLIBC__) && __GLIBC_PREREQ(2, 25)
-	if(getrandom(bytes, count, 0) == 0){
+	if(getrandom(bytes, count, 0) == count){
 		rc = MOSQ_ERR_SUCCESS;
 	}
 #elif defined(WIN32)