knownhosts: resolve leaks found by coverity

src/kex.c

@@ -390,8 +390,10 @@ static char *ssh_client_select_hostkeys(ssh_session session){
     int needcoma=0;
 
     methods = ssh_knownhosts_algorithms(session);
-	if (methods == NULL || methods[0] == NULL)
+	if (methods == NULL || methods[0] == NULL){
+		SAFE_FREE(methods);
 		return NULL;
+	}
 
 	for (i=0;preferred_hostkeys[i] != NULL; ++i){
 		for (j=0; methods[j] != NULL; ++j){

src/known_hosts.c

@@ -678,21 +678,18 @@ char **ssh_knownhosts_algorithms(ssh_session session) {
   }
 
   if (session->opts.host == NULL) {
-    return 0;
+    return NULL;
   }
 
   host = ssh_lowercase(session->opts.host);
   hostport = ssh_hostport(host, session->opts.port);
-  if (host == NULL || hostport == NULL) {
+  array = malloc(sizeof(char *) * KNOWNHOSTS_MAXTYPES);
+
+  if (host == NULL || hostport == NULL || array == NULL) {
     ssh_set_error_oom(session);
     SAFE_FREE(host);
     SAFE_FREE(hostport);
-    return NULL;
-  }
-
-  array = malloc(sizeof(char *) * KNOWNHOSTS_MAXTYPES);
-  if (array==NULL){
-	  ssh_set_error_oom(session);
+    SAFE_FREE(array);
     return NULL;
   }