Example: for a file asm/foo.c, make will look for asm/arm/foo.[cS] and
compile it if found. If not found it'll fall back to asm/foo.c.
Also introduce new ARCH make variable. This is automatically detected by
configure. It is distinct from CPU since CPU defines the dir used for
the target tree (i.e. firmware/target/X, so it can be "hosted").
ARCH really has the target isa and can be x86 for sims/raaa too.
Change-Id: I18e5d2b7b7bbc2ad2be551a74a0fcae5ffbcbf8b
This dir is suitable for stuff that doesn't fit the target tree, e.g. because
it also builds on hosted or otherwise. It also has a generic subfolder for
fallback C implementations so that not all archs need to provide asm files.
SOURCES should only contain "foo.c" where foo.c includes the specific
<arch>/foo.c files from the subdirs using the preprocessor. This way automatic
selection of asm versions or generic C verion is possible.
For the start, the thread support files are moved, since ASM threads can
be used on hosted platforms as well. Since core_sleep() remains platform
specific it's moved to the corresponding system.h headers.
Change-Id: Iebff272f3407a6eaafeb7656ceb0ae9eca3f7cb9
