err: rename err_load_xxx_strings_int functions

The new names are ossl_err_load_xxx_strings.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15446)
diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c
index 595e9f5..014eda0 100644
--- a/ssl/ssl_err.c
+++ b/ssl/ssl_err.c
@@ -559,7 +559,7 @@
 
 #endif
 
-int err_load_SSL_strings_int(void)
+int ossl_err_load_SSL_strings(void)
 {
 #ifndef OPENSSL_NO_ERR
     if (ERR_reason_error_string(SSL_str_reasons[0].error) == NULL)