MacOS compilation fails miserably

[GoogleCodeExporter]

Compilation fails on recent versions of MacOS.

Multiple sources of problems:
-DOS_MACOSX missing in Makefile
- Usage of lots of nonstandard include files:
  * base/port.h:#include <byteswap.h>
  * base/stl_decl_macosx.h:    
    #include <bits/stl_tempbuf.h>
    #include <ext/functional>
    #include <ext/hash_fun.h>
    #include <ext/hashtable.h>

I'm using the current version of s2-geometry-library.
Will be happy to help, owners/admins please let be in touch if interested.

OS and compiler:
$ uname -a
Darwin gwesp 13.4.0 Darwin Kernel Version 13.4.0: Sun Aug 17 19:50:11 PDT 2014; 
root:xnu-2422.115.4~1/RELEASE_X86_64 x86_64

$ g++ --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr 
--with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin13.4.0
Thread model: posix

Original issue reported on code.google.com by gew...@gmail.com on 24 Feb 2015 at 6:26