unittests: make test macros save for strict aliasing
Merge pull request #1973 from authmillenon/test-macros

embunit: make test macros save for strict aliasing
c++: sys: add extern C to header files
Merge pull request #1793 from BytesGalore/extern_C_in_headers_sys

sys: add extern "C" to headers
6lowpan: free fragment buffer in error case
6lowpan: fix buffer overrun in decompression
IPv6: allow complete in ipv6_addr_init_prefix

If the specified prefix is a full IPv6 address, no bits remain.
Fixes a possible buffer overrun.
net_if: fix buffer overruns
6lowpan: do not overrun in context_remove