Add missing includes to fix compile errors

fs.cpp:35:17: error: no member named 'strerror' in namespace 'std'
    return std::strerror(errno);
           ~~~~~^
fs.cpp:49:9: error: use of undeclared identifier 'close'
        close(fd);
        ^
2 errors generated.

./interfaces/chain.h:265:55: error: ‘std::function’ has not been declared
     virtual void rpcRunLater(const std::string& name, std::function<void()> fn, int64_t seconds) = 0;
                                                       ^~~

0 files changed, 0 insertions, 0 deletions