[462154] Fix problems parsing config strings with leading spaces.

Thanks to Aidan Gill.

Bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=462154

ChangeLog.txt

@@ -1,5 +1,7 @@
 Broker:
 - Fix possible crash when using pattern ACLs.
+- Fix problems parsing config strings with multiple leading spaces. Closes
+  #462154.
 
 Client library:
 - Inflight limits should only apply to outgoing messages. Closes #461620.

src/conf.c

@@ -1967,6 +1967,10 @@ static int _conf_parse_string(char **token, const char *name, char **value, char
 			_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Error: Duplicate %s value in configuration.", name);
 			return MOSQ_ERR_INVAL;
 		}
+		/* Deal with multiple spaces at the beginning of the string. */
+		while((*token)[0] == ' '){
+			(*token)++;
+		}
 		*value = _mosquitto_strdup(*token);
 		if(!*value){
 			_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Error: Out of memory.");