mingw build is currently broken

[Tor Lillqvist]

Please note that the breakage comes when doing the *buld* platform
part of the cross-compilation. I.e. when building those build-time
tools that are used by the LibreOffice build process. There tools
obviously need to be built for the *build* platform. It is not as such
related to cross-compiling, but to building Linux tools (the MinGW
cross-compiling tinderbox runs Linux).

It am fairly sure that the breakage is a consequence of the recently
introduced dependency on the svt and tl libraries to the helplinker
library. (When cross-compiling for MinGW, help is built, too, it
seems, so the helpcompiler tools are needed, built for the build
platform.) Unfortunately that then seems to drag in a huge amount of
more code. I have been adding them one by one to the
Module_cross_tail_build.mk, but it is tedious as I only have the MinGW
tinderbox log to go after...

--tml