tcptls: Prevent crash when freeing OpenSSL errors.

write_openssl_error_to_log has been erroneously
using ast_free instead of free, which will
cause a crash when MALLOC_DEBUG is enabled since
the memory was not allocated by Asterisk's memory
manager. This changes it to use the actual free
function directly to avoid this.

ASTERISK-30278 #close

Change-Id: Iac8b6468b718075809c45d8ad16b101af21a474d

main/tcptls.c

@@ -126,7 +126,7 @@ static void write_openssl_error_to_log(void)
 		ast_log(LOG_ERROR, "%.*s\n", (int) length, buffer);
 	}
 
-	ast_free(buffer);
+	ast_std_free(buffer);
 }
 #endif