test/x509aux.c: Fix argv loop

There are cases when argc is more trustable than proper argv termination.
Since we trust argc in all other test programs, we might as well treat it
the same way in this program.
Reviewed-by: NMatt Caswell <matt@openssl.org>

test/x509aux.c

@@ -180,7 +180,6 @@ static int test_certs(BIO *fp)
 int main(int argc, char *argv[])
 {
     BIO *bio_err;
-    const char *certfile;
     const char *p;
     int ret = 1;
 
@@ -197,24 +196,30 @@ int main(int argc, char *argv[])
         CRYPTO_set_mem_debug(1);
     CRYPTO_mem_ctrl(CRYPTO_MEM_CHECK_ON);
 
-    while ((certfile = *++argv) != NULL) {
-        BIO *f = BIO_new_file(certfile, "r");
+    argc--;
+    argv++;
+
+    while (argc >= 1) {
+        BIO *f = BIO_new_file(*argv, "r");
         int ok;
 
         if (f == NULL) {
             fprintf(stderr, "%s: Error opening cert file: '%s': %s\n",
-                    progname, certfile, strerror(errno));
+                    progname, *argv, strerror(errno));
             EXIT(ret);
         }
         ret = !(ok = test_certs(f));
         BIO_free(f);
 
         if (!ok) {
-            printf("%s ERROR\n", certfile);
+            printf("%s ERROR\n", *argv);
             ret = 1;
             break;
         }
-        printf("%s OK\n", certfile);
+        printf("%s OK\n", *argv);
+
+        argc--;
+        argv++;
     }
 
 #ifndef OPENSSL_NO_CRYPTO_MDEBUG