restrict the DLLs we load on win32 to avoid those with known vulnerabilities

[Antoine Martin]

For example: ​flac changelog: Fix CVE-2014-9028 (heap write overflow) and CVE-2014-8962 (heap read overflow) in 1.3.1

Related to:

• #544: jpeg and png are out of date..
• #678: gtk3 build from source
• #300: gtk2 build from source
• #299: gstreamer build from source

We should at least exclude flac on win32, it would also be a good idea to inspect all the media libraries we ship and blacklist the ones that are too out of date / vulnerable (hopefully this will leave some we can still use).

[Antoine Martin]

r8163 avoids flac on win32 with gstreamer 0.10 - should be backported.

We now need to go through the rest of the dlls..

[Antoine Martin]

Backport in r8501.

[Antoine Martin]

With the number of dlls we cannot replace since we cannot build GTK2 from source, I think it is just too hard to make the win32 safe.
We need either a native client (pure pywin32?) or use GTK3 (#640).

[migration script]

this ticket has been moved to: ​https://github.com/Xpra-org/xpra/issues/749