This commit makes it possible to successfully run "make all" against ytools' again, with TARGET_TUPLE set to i686-ms-w64-mingw. Lots of minor and major tweaks here and there.
The biggest diff is a move of the architecture-related definitions into platform.mk. The are needed pretty early on, so that seems reasonable.
Making this work again is part of the larger effort to support cross buildchains in a more concise way, i.e. without so many if ($(TARGET),mingw)) all over the place. TARGET's relevance should dwindle, until it's finally taken over by the TARGET_XXX variables extracted from TARGET_TUPLE or TARGET_TRIPLET.
Signed-off-by: Jan Lindemann <jan@janware.com>