Find proper version of exchndl.dll to bundle

The exchndl.dll bundled with 2.1.21 is too new for Vista and XP, because those two OSes use a dbghelp.dll that does not contain a required function. XP/Vista pops up this error. OSes Win7+ are not affected by this.

Our options are:

1. Bundle an older exchndl.dll with SRB2
   • Alam does not want this, because RPT files will break on new Release builds.
2. Bundle the newest exchndl.dll as well as a new dbghelp.dll to satisfy the dependency.
   • Disallowed by licensing; need to bundle an MSI
3. Bundle the newest exchndl.dll and direct XP/Vista users to install the Win7 SDK.
   • Really not an option because that install requires 500 MB?
4. Ignore the popup error, because it doesn't prevent SRB2 from running anyway.
5. Block exchndl.dll from loading on XP/Vista.

Based on this issue, the last exchndl version we could use for XP/Vista is 0.6.4. However, for 64-bit, the earliest exchndl version available is 0.6.5. Therefore, 64-bit XP/Vista users would be locked out. (I read the changelog wrong, rip)

We also need to test if exchndl works on Wine.

The reason to upgrade exchndl from 2.1.20's version is because, according to Alam, that exchndl version required SRB2 to be built with an old toolchain. I don't know the details, there. I think exchndl's version was older than 0.4.3, but I'm not sure because the DLL properties does not say.