No matter how broken iOS is in CMake 3.6, $<CONFIG> seems to work there,
so reducing the amount of code and putting the configure into a single
place independently of what generator or what system/build is used.
Compared to current state it always adds Debug/configure.h instead of
putting it directly to the ${CMAKE_CURRENT_BINARY_DIR}, but the
alternative would be some CMake branching again and I just removed that,
so no.
This also prepares everything for plugin libraries being put into a
central place -- the config files don't depend on their location
anymore.
Vladimír Vondruš
a018521a8c
