keyval_parse.c: ensure to init values

Coverity complained about uninitialized variables; ensure that they
are initialized to 0 in all cases.

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

opal/util/keyval_parse.c

@@ -14,6 +14,7 @@
  *                         reserved.
  * Copyright (c) 2018      Triad National Security, LLC. All rights
  *                         reserved.
+ * Copyright (c) 2020      Cisco Systems, Inc.  All rights reserved
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -276,7 +277,7 @@ static int save_param_name (void)
 
 static int add_to_env_str(char *var, char *val)
 {
-    int sz, varsz, valsz, new_envsize;
+    int sz, varsz = 0, valsz = 0, new_envsize;
     void *tmp;
 
     if (NULL == var) {