snprintf() length fix for info

The important part of this fix is a couple places 5 was hard-coded that needed to be
strlen(OPAL_INFO_SAVE_PREFIX).

But also this contains a fix for a gcc 7.3.0 compiler warning about snprintf(). There
was an "if" statement making sure all the arguments had appropriate strlen(), but gcc
still complained about the following snprintf() because the size of the struct element
is iterator->ie_key[OPAL_MAX_INFO_KEY + 1].

Signed-off-by: Mark Allen <markalle@us.ibm.com>

opal/util/info.c

@@ -176,7 +176,7 @@ int opal_info_dup_mode (opal_info_t *info, opal_info_t **newinfo,
 {
     int err, flag;
     opal_info_entry_t *iterator;
-    char savedkey[OPAL_MAX_INFO_KEY];
+    char savedkey[OPAL_MAX_INFO_KEY + 1]; // iterator->ie_key has this as its size
     char savedval[OPAL_MAX_INFO_VAL];
     char *valptr, *pkey;
     int is_IN_key;
@@ -194,7 +194,7 @@ int opal_info_dup_mode (opal_info_t *info, opal_info_t **newinfo,
          if (0 == strncmp(iterator->ie_key, OPAL_INFO_SAVE_PREFIX,
              strlen(OPAL_INFO_SAVE_PREFIX)))
         {
-             pkey += 5;
+             pkey += strlen(OPAL_INFO_SAVE_PREFIX);
 
              is_IN_key = 1;
              exists_IN_key = 1;
@@ -207,9 +207,9 @@ int opal_info_dup_mode (opal_info_t *info, opal_info_t **newinfo,
              exists_reg_key = 1;
 
 // see if there is an __IN_<key> for the current <key>
-             if (strlen(iterator->ie_key) + 5 < OPAL_MAX_INFO_KEY) {
-                 snprintf(savedkey, OPAL_MAX_INFO_KEY,
-                     OPAL_INFO_SAVE_PREFIX "%s", iterator->ie_key);
+             if (strlen(OPAL_INFO_SAVE_PREFIX) + strlen(pkey) < OPAL_MAX_INFO_KEY) {
+                 snprintf(savedkey, OPAL_MAX_INFO_KEY+1,
+                     OPAL_INFO_SAVE_PREFIX "%s", pkey);
 // (the prefix macro is a string, so the unreadable part above is a string concatenation)
                  opal_info_get_nolock (info, savedkey, OPAL_MAX_INFO_VAL,
                                        savedval, &flag);