update to compile with libc++abi and clang
Couple of CMake-related bugfixes.
Added ability for c++abi linker flags if HAVE_LIBC++ABI is set
allow cryptest to use libc++abi
define _POSIX_PATH_MAX 256 if not defined (clang )
Merge branch 'next' of git://github.com/maidsafe/MaidSafe into libcxxabi_update
ignore unused command line args when compiling (affects clang libc++abi)
Merge branch 'next' into leveldb_update
Merge.