relocatable kdoctools

[Harald Sitter]

Ahoy ahoy

I've just stumbled upon a rather puzzling situation with kdoctools. It
has code branching to turn its assets relocatable [1] (i.e. resolve
paths relative rather than hardcode their location). Now the weird bit
about this is that it is only used on windows.

The reason this puzzles me is that the relocatable code for Windows
would work just fine for Linux and OSX, from what I can tell there is
no real downside to it besides the additional code, which we need
anyway. On the other hand, the conditional treatment of Windows gives
the Windows code branch substantially less implicit run exposure (i.e.
most devs/testers aren't on Windows, so fewer people build the
relevant if-branch).

With that in mind: how about we drop the harcoding code path and make
the Windows code path the default and have kdoctools assets always be
relocatable?

[1] https://phabricator.kde.org/source/kdoctools/browse/master/src/CMakeLists.txt;8c32e153fae80186375d83dbab82bcfc228b1484$9