qga: use wide-chars constants for wchar_t comparisons

Reported-by: NLaszlo Ersek <lersek@redhat.com>
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NLaszlo Ersek <lersek@redhat.com>
Reviewed-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

qga/commands-win32.c

@@ -1323,8 +1323,10 @@ get_net_error_message(gint error)
     if (msg != NULL) {
         nchars = wcslen(msg);
 
-        if (nchars > 2 && msg[nchars-1] == '\n' && msg[nchars-2] == '\r') {
-            msg[nchars-2] = '\0';
+        if (nchars > 2 &&
+            msg[nchars - 1] == L'\n' &&
+            msg[nchars - 2] == L'\r') {
+            msg[nchars - 2] = L'\0';
         }
 
         retval = g_utf16_to_utf8(msg, -1, NULL, NULL, NULL);