jw-build doesn't stop at building software, packaging it afterwards is also a core feature, so this commit gives the package a better name.
The commit replaces strings s/jw-build/jw-pkg/ in text files and file names. Fallout to the functionality is fixed, variable names are left as they are, though. To be adjusted by later commits.
This commit takes the MinGW cross compilation further into the direction of being a more general framework for cross compilation. Changed some variable names that are too specialized, notably MinGW tool chain directories, compilers, utilities.
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.
C++ definitions are numerous, and they shouldn't pollute variable space and performance outside of directories containing C++ files. This commit pushes them into a defs-cpp.mk file.