Make code more portable and port to cygwin

Make code more portable and port to cygwin

arch/alpha/alpha_tru64_process.cc:
    getdirent isn't implemented by cygwin.  panic if this function is
    executed.  (It shouldn't be too much to emulate it using opendir,
    readdir, etc.)
arch/alpha/pseudo_inst.cc:
    Use lseek once and read instead pread.
base/intmath.hh:
    we want int, long, and long long variations of FloorLog2 instead
    of int32_t, int64_t.  Otherwise, we leave one out.
base/socket.cc:
    Fix define that seems to be for apple
sim/serialize.cc:
    don't use the intXX_t stuff, instead, use the real types
    so we're sure that we cover all of them.

--HG--
extra : convert_revision : 9fccaff583100b06bbaafd95a162c4e19beed59e