decklink: Fix string handling causing plugin to not function

plugins/decklink/win/platform.cpp

@@ -1,6 +1,7 @@
 #include "../platform.hpp"
 
 #include <util/platform.h>
+#include <comdef.h>
 
 IDeckLinkDiscovery *CreateDeckLinkDiscoveryInstance(void)
 {
@@ -31,11 +32,10 @@ bool DeckLinkStringToStdString(decklink_string_t input, std::string &output)
 	if (input == nullptr)
 		return false;
 
-	size_t len = wcslen(input);
-	size_t utf8_len = os_wcs_to_utf8(input, len, nullptr, 0);
+	char *out = _com_util::ConvertBSTRToString(input);
+	output = std::string(out);
 
-	output.resize(utf8_len);
-	os_wcs_to_utf8(input, len, &output[0], utf8_len);
+	delete[] out;
 
 	return true;
 }