Compile with -Wstrict-prototypes for mspgcc and armgcc toolchains

Adds `-Wstrict-prototypes` for mspgcc and armgcc toolchains and fixes the arising warnings for

* telosb
* z1
* gina
* wsn430v13b
* wsn430v14
* iot-lab_M3
* cc2538

Had to touch SConscript.env for python board too, please double check.

Since I don't have a copy of iar or iar-proj toolchains I couldn't test against them, please let me know if issues arise when compiling with these.