msp430: provide oneway-malloc implicitly

For MSP430 boards oneway-malloc is already used *if* `malloc.h` was
included. The problem is that `malloc.h` is not a standard header, even
though it is common. `stdlib.h` in the right place to look for
`malloc()` and friends.

This change removes this discrepancy. `malloc()` is just named like
that, without the leading underscore. The symbols now are weak, which
means that they won't override library functions if MSP's standard
library will provide these functions at some point. (Unlikely, since
using `malloc()` on tiny systems is less then optimal ...)

Closes #1061 and #863.
Add doxygen comments to MSP's oneway malloc
msp/tests: remove blacklist from test_bloom_bytes

Issue #1061 was fixed.
Merge pull request #1182 from Kijewski/msp-oneway-malloc

msp430: provide oneway-malloc implicitly
 make: remove clutter

Remove some outdated example code.
 make: add `BOARD_INSUFFICIENT_RAM` blacklisting

Currently most blacklistings for examples and tests are done because the
board provides too little RAM or ROM. Besides of the actual linking all
the compiling should nevertheless work just fine.

This PR adds the variable `BOARD_INSUFFICIENT_RAM` to tell the
`buildtest` to compile the code for a board, but omit the linking step.
Use `BOARD_INSUFFICIENT_RAM` in examples and tests
Merge pull request #1039 from Kijewski/buildtest-insufficient-ram

make: add `BOARD_INSUFFICIENT_RAM` blacklisting
make: buildtest with "-Wall -Wextra -Werror"

Make buildtests more pedantic by supplying `-Wall -Wexta -Werror` by default.
This can be disabled through `make W_ALL=0 W_EXTRA=0 W_ERROR=0`, resp.,
or with `make W_NONE=1`, which disables every extra flag.
With `make PEDANTIC=1 PEDANTIC_ERRORS=1` you can make the buildtest even more
pedantic.

Also the generic make variable `W_FLAGS` is added, through which extra
`CFLAGS` can be supplied in the normal `make all`.