libc: removing newlib, adding BSD libc
posixcompat: moving gettimeofday to libc
harness: adding a simple math test
lwip, lwip2: moving includes to /include, compiling with BSD headers

Signed-off-by: Adam Turowski <adam.turowski@inf.ethz.ch>

headers: wrap declarations in extern "C".

Note: this change is not exhaustive and only touches some headers in //include

Merge from ASPLOS tree.