Currrently native overrides the object file targets, because it needs
the different include paths to interact with libc and the OS.
This PR simplifies their makefiles to only override the variable
INCLUDES, instead of overriding the targets.
For many modules the `Makefile` contains a line like
```
MODULE:=$(shell basename $(CURDIR))
```
This conclusively shows that we do not have to set the module name
manually.
This PR removes the need to set the module name manually, if it is the
same as the basename. E.g. for `…/sys/vtimer/Makefile` the variable
make `MODULE` will still be `vtimer`, because it is the basename of the
Makefile.
native modules will never need the dynamic INCLUDES, so we define our
own NATIVEINCLUDES. Due to the current make structure, the only way to
not use INCLUDES is to redefine the build rules.
wrap some libc functions that do system calls (terminal output)
wrap read/write with syscall guard
define real_read/write (next dynamic linker find for read/write)
guard system calls in remaining code
introduce native_internhal.h
throw out some debug statements that break things
clean up includes a bit
declare board_init in native_internhal.h
add -ldl to LINKFLAGS for cpu/syscalls
make some variables volatile
remove rx_buffer_next from header
more DEBUG output
fix warnings
coding conventions
change puts to DEBUG
rename end-context/stack
