The helplinker library has grown a dependency on the svt and tl libraries. But
the helpcompiler module is needed to be built for the BUILD platform only if
the HOST platform's BUILD_TYPE includes DESKTOP (or only if its BUILD_TYPE
includes HELP?).

We used to build helpcompiler and some other things for the BUILD platform
depending on whether the BUILD platform's BUILD_TYPE included DESKTOP.

Also, codemaker should surely be built for BUILD unconditionally, ant xmlhelp
presumably not at all.

Change-Id: I3df995ce6b92da4ce9eb35115cf3e8560e06f292