DOSBox build failure notes on OS X 10.11

dosbox_build.md

No workee with debug on 10.11.4, will check 10.11.5

```
$ brew reinstall dosbox --with-debugger
==> Reinstalling homebrew/games/dosbox with --with-debugger
==> Downloading https://downloads.sourceforge.net/project/dosbox/dosbox/0.74/dosbox-0.74.tar.gz
Already downloaded: /Users/bsk/Library/Caches/Homebrew/dosbox-0.74.tar.gz
==> ./configure --prefix=/usr/local/Cellar/dosbox/0.74 --disable-sdltest --enable-core-inline --enable-debug --disable-dynrec
==> make install
Last 15 lines from /Users/bsk/Library/Logs/Homebrew/dosbox/02.make:
                            ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/curses.h:322:16: note: forward declaration of '_win_st'
typedef struct _win_st WINDOW;
               ^
debug_gui.cpp:157:22: error: member access into incomplete type 'WINDOW' (aka '_win_st')
        mvaddstr(dbg.win_out->_begy-1,0, "---(OutPut/Input    Scroll: home/end    )---");
                            ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/curses.h:322:16: note: forward declaration of '_win_st'
typedef struct _win_st WINDOW;
               ^
5 errors generated.
make[2]: *** [debug_gui.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [install-recursive] Error 1
make: *** [install-recursive] Error 1

READ THIS: https://git.io/brew-troubleshooting
If reporting this issue please do so at (not Homebrew/brew):
  https://github.com/Homebrew/homebrew-games/issues

These open issues may also help:
dosbox-x failed to build on OS X 10.11 https://github.com/Homebrew/homebrew-games/issues/527
```

```
$ brew reinstall dosbox
==> Reinstalling homebrew/games/dosbox
==> Downloading https://downloads.sourceforge.net/project/dosbox/dosbox/0.74/dosbox-0.74.tar.gz
Already downloaded: /Users/bsk/Library/Caches/Homebrew/dosbox-0.74.tar.gz
==> ./configure --prefix=/usr/local/Cellar/dosbox/0.74 --disable-sdltest --enable-core-inline --disable-dynrec
==> make install
==> Caveats
DOSBox is not built for optimal performance due to unstability on 64-bit platform.
==> Summary
🍺  /usr/local/Cellar/dosbox/0.74: 8 files, 2.3M, built in 39 seconds
```