BUILD/MINOR: ssl: shut up a build warning about format truncation

Actually gcc believes it has detected a possible truncation but it
cannot since the output string is necessarily at least one char
shorter than what it expects. However addressing it is easy and
removes the need for an intermediate copy so let's do it.

(cherry picked from commit 0580052bb6f9c924daedfe62d779eade68677adf)
Signed-off-by: Willy Tarreau <w@1wt.eu>
diff --git a/src/ssl_sock.c b/src/ssl_sock.c
index 01e539a..ea84ec9 100644
--- a/src/ssl_sock.c
+++ b/src/ssl_sock.c
@@ -3678,25 +3678,23 @@
 					}
 
 					if (is_bundle) {
-						char dp[MAXPATHLEN+1] = {0}; /* this will be the filename w/o the keytype */
 						int dp_len;
 
 						dp_len = end - de->d_name;
-						snprintf(dp, dp_len + 1, "%s", de->d_name);
 
 						/* increment i and free de until we get to a non-bundle cert
 						 * Note here that we look at de_list[i + 1] before freeing de
-						 * this is important since ignore_entry will free de
+						 * this is important since ignore_entry will free de. This also
+						 * guarantees that de->d_name continues to hold the same prefix.
 						 */
-						while (i + 1 < n && !strncmp(de_list[i + 1]->d_name, dp, dp_len)) {
+						while (i + 1 < n && !strncmp(de_list[i + 1]->d_name, de->d_name, dp_len)) {
 							free(de);
 							i++;
 							de = de_list[i];
 						}
 
-						snprintf(fp, sizeof(fp), "%s/%s", path, dp);
+						snprintf(fp, sizeof(fp), "%s/%.*s", path, dp_len, de->d_name);
 						cfgerr |= ssl_sock_load_multi_cert(fp, bind_conf, NULL, NULL, 0, err);
-
 						/* Successfully processed the bundle */
 						goto ignore_entry;
 					}