Avoid surpising password dialog in X509 file lookup.

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4111)

crypto/x509/by_file.c

@@ -88,7 +88,7 @@ int X509_load_cert_file(X509_LOOKUP *ctx, const char *file, int type)
 
     if (type == X509_FILETYPE_PEM) {
         for (;;) {
-            x = PEM_read_bio_X509_AUX(in, NULL, NULL, NULL);
+            x = PEM_read_bio_X509_AUX(in, NULL, NULL, "");
             if (x == NULL) {
                 if ((ERR_GET_REASON(ERR_peek_last_error()) ==
                      PEM_R_NO_START_LINE) && (count > 0)) {
@@ -145,7 +145,7 @@ int X509_load_crl_file(X509_LOOKUP *ctx, const char *file, int type)
 
     if (type == X509_FILETYPE_PEM) {
         for (;;) {
-            x = PEM_read_bio_X509_CRL(in, NULL, NULL, NULL);
+            x = PEM_read_bio_X509_CRL(in, NULL, NULL, "");
             if (x == NULL) {
                 if ((ERR_GET_REASON(ERR_peek_last_error()) ==
                      PEM_R_NO_START_LINE) && (count > 0)) {
@@ -200,7 +200,7 @@ int X509_load_cert_crl_file(X509_LOOKUP *ctx, const char *file, int type)
         X509err(X509_F_X509_LOAD_CERT_CRL_FILE, ERR_R_SYS_LIB);
         return 0;
     }
-    inf = PEM_X509_INFO_read_bio(in, NULL, NULL, NULL);
+    inf = PEM_X509_INFO_read_bio(in, NULL, NULL, "");
     BIO_free(in);
     if (!inf) {
         X509err(X509_F_X509_LOAD_CERT_CRL_FILE, ERR_R_PEM_LIB);