Merge pull request #691 from Lotterleben/test-569

added two test cases for issue #100
fix test_irq Makefile

closes #696
Merge pull request #699 from LudwigOrtmann/issue_696

fix test_irq Makefile
Do not mandate input language

An application might want to use C11 features. The user would assume
that setting `CFLAGS=-std=gnu11` in the Makefile would work. It does not
since the board's Makefile.include shadows the `-std` flag.

This patch removes the `-std=gnu99` from the various Makefile.includes,
and sets the flag in the common Makefile.include of RIOT instead.
If an `-std` flag was provided by an earlier Makefile (the application,
the board, or the CPU [whilst only the former one should]), then no
additional flag is set. It is first tested if the supplied compiler
understands `-std=gnu99`, then `-std=c99`.
Use `filter` instead of `findstring`

See #672
Introduce board blacklists and board whitelists
Function attributes are now defined elsewhere ("attributes.h")
Implemented reboot() function for ARM-based MCUs
Added while(1) to ensure GCC valids NORETURN; fixed indentation
Eliminate findstring in more places
Split `} else {` lines per #693
Merge pull request #692 from Kijewski/std-flag

Do not mandate input language
Merge pull request #576 from Kijewski/usepkg

Add USEPKG variable for Makefiles
https://github.com/Kijewski/RIOT/commit/102dc453828012985f82915ad826be069f444e61#commitcomment-5378590
implement rudimentary native reboot
Added while(1) to ensure GCC valids NORETURN; fixed indentation
Merge pull request #1 from LudwigOrtmann/native_reboot

implement rudimentary native reboot
add system calls to the shell
Merge pull request #2 from LudwigOrtmann/shell_syscalls

add system calls to the shell (to implement a reboot command)
replace all endless for loops by while