pkcs12 demo: output correct file names on error.

CLA: Trivial

Reviewed-by: Richard Levitte <[email protected]>
Reviewed-by: Paul Dale <[email protected]>
(Merged from openssl#11304)

Author: ning

demos/pkcs12/pkread.c

@@ -79,7 +79,7 @@ int main(int argc, char **argv)
     name = find_friendly_name(p12);
     PKCS12_free(p12);
     if ((fp = fopen(argv[3], "w")) == NULL) {
-        fprintf(stderr, "Error opening file %s\n", argv[1]);
+        fprintf(stderr, "Error opening file %s\n", argv[3]);
         goto err;
     }
     if (name != NULL)

demos/pkcs12/pkwrite.c

@@ -42,7 +42,7 @@ int main(int argc, char **argv)
         exit(1);
     }
     if ((fp = fopen(argv[4], "wb")) == NULL) {
-        fprintf(stderr, "Error opening file %s\n", argv[1]);
+        fprintf(stderr, "Error opening file %s\n", argv[4]);
         ERR_print_errors_fp(stderr);
         exit(1);
     }