Installing our CLI DLLs on Windows XP SP3 with .NET 2.0 and 3.5 (but no newer) fails

[Tor Lillqvist]

> You probably built with .NET 4.0 SDK.

Well, I tried hard not to, and the versions I see output by the tools
don't indicate that 4.0 would be used, but yeah, either I didn't look
in the right place or somehow otherwise that crept in.

(Also the TDF build of the 4.0.0 beta1 has the same problem.)

> Either we can bump this (REQUIRED_DOTNET_VERSION) to 4.0.0.0

We could do that, but on the other hand, as you say, given how rarely
used the LibreOffice CLI stuff is likely to be anyway, it would be a
bit silly to require the newest .NET just for installing LO even if
for most people it is not used at run-time at all.

--tml