* Szabolcs Nagy <nsz@port70.net> [2014-02-07 00:31:22 +0100]:
> 
> VPATH=$(SOMEDIR)
> %.o: $(ARCH)/%.s
> 

attached a make diff that can do out-of-tree build, by specifying
M=relative/path/to/musl

- config is not ready
- directory creation is a hack
- include/bits/alltypes.h is generated into the original repo
(include/bits is a symlink to the arch/bits dir)