Fix curl 421 errors when disabling verify peer

```
== Info: WARNING: disabling hostname validation also disables SNI.
```
which leads to a "431 Misdirected Request" reply for servers
with shared hosting.

gtk2_ardour/pingback.cc

@@ -103,9 +103,6 @@ _pingback (void *arg)
 
 #ifdef MIXBUS
 	curl_easy_setopt (h.curl (), CURLOPT_FOLLOWLOCATION, 1);
-	/* do not check cert */
-	curl_easy_setopt (h.curl (), CURLOPT_SSL_VERIFYPEER, 0);
-	curl_easy_setopt (h.curl (), CURLOPT_SSL_VERIFYHOST, 0);
 #endif
 
 	ping_call* cm = static_cast<ping_call*> (arg);

libs/ardour/soundcloud_upload.cc

@@ -348,8 +348,5 @@ SoundcloudUploader::setcUrlOptions()
 	// Allow connections to time out (without using signals)
 	curl_easy_setopt(curl_handle, CURLOPT_NOSIGNAL, 1);
 	curl_easy_setopt(curl_handle, CURLOPT_CONNECTTIMEOUT, 30);
-
-	curl_easy_setopt(curl_handle, CURLOPT_SSL_VERIFYHOST, 0);
-	curl_easy_setopt(curl_handle, CURLOPT_SSL_VERIFYPEER, 0);
 }
 

libs/pbd/ccurl.cc

@@ -96,6 +96,10 @@ CCurl::curl () const
 void
 CCurl::ca_setopt (CURL* c)
 {
+#if defined PLATFORM_WINDOWS || defined __APPLE__
+	/* winSSL and DarwinSSL does not need this, use defaults w/VERIFYHOST */
+	return;
+#endif
 	if (ca_info) {
 		curl_easy_setopt (c, CURLOPT_CAINFO, ca_info);
 	}