schannel: fix compiler warning

When building with Unicode on MSVC, the compiler warns about freeing a
pointer to const in Curl_unicodefree. Fix this by declaring it as
non-const and casting the argument to Curl_convert_UTF8_to_tchar to
non-const too, like we do in all other places.

Closes https://github.com/curl/curl/pull/3435

diff --git a/lib/vtls/schannel_verify.c b/lib/vtls/schannel_verify.c
index 8b21624ba4a16489810a8c96375019071057b44d..680f6ec5d6f2a58828f2cf55619dc1907cfc86c0 100644 (file)
--- a/lib/vtls/schannel_verify.c
+++ b/lib/vtls/schannel_verify.c
@@ -7,7 +7,7 @@
  *
  * Copyright (C) 2012 - 2016, Marc Hoersken, <info@marc-hoersken.de>
  * Copyright (C) 2012, Mark Salisbury, <mark.salisbury@hp.com>
- * Copyright (C) 2012 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 2012 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -87,14 +87,14 @@ static CURLcode add_certs_to_store(HCERTSTORE trust_store,
   LARGE_INTEGER file_size;
   char *ca_file_buffer = NULL;
   char *current_ca_file_ptr = NULL;
-  const TCHAR *ca_file_tstr = NULL;
+  TCHAR *ca_file_tstr = NULL;
   size_t ca_file_bufsize = 0;
   DWORD total_bytes_read = 0;
   bool more_certs = 0;
   int num_certs = 0;
   size_t END_CERT_LEN;
 
-  ca_file_tstr = Curl_convert_UTF8_to_tchar(ca_file);
+  ca_file_tstr = Curl_convert_UTF8_to_tchar((char *)ca_file);
   if(!ca_file_tstr) {
     failf(data,
           "schannel: invalid path name for CA file '%s': %s",