How to build a bufferevent-enabled Tor on windows XP in way too many easy steps

You will need:
 - The latest version of:
   - MinGW, openssl, zlib, libevent (at least version 2.0.12 or a git
     checkout that includes my patches), tor (at least version 0.2.3.1 or
     a git checkout of the master branch)
 - Windows XP
 - time
 
You will want to:
 - Install MinGW into C:\MinGW. If you pick a different path, pick
   one without spaces. During the installation, make sure you select
   the msys option, it is disabled by default.
 - Start a MinGW Shell: Start -> All Programs -> MinGW Shell
 - Use the mingw-get tool to install a bunch of required programs:

   $ mingw-get install autoconf automake libtool msys-wget msys-vim

 - make a build directory, fetch zlib, openssl and libevent. Extract.

 - build & install zlib. Enjoy this straightforward procedure. Don't
   export any of the variables or you might have fun conflicts later:

   $ BINARY_PATH=/usr/local/bin INCLUDE_PATH=/usr/local/include \
     LIBRARY_PATH=/usr/local/lib make -f win32/Makefile.gcc

   $ BINARY_PATH=/usr/local/bin INCLUDE_PATH=/usr/local/include \
     LIBRARY_PATH=/usr/local/lib make install -f win32/Makefile.gcc

 - patch openssl to create useful DLLs (if you don't do this, DLLs
   will be created for you. Unfortunately, they won't contain any
   exported symbols and are thus pretty worthless):
 
   $ vim Configure
   
   look for this line (without the '):
   
   '"mingw", "gcc:-mno-cygwin -DL_ENDIAN -DWIN32_LEAN_AND_MEAN -fomit-frame-pointer -O3 -march=i486 -Wall::-D_MT:MINGW32:-lws2_32 -lgdi32 -lcrypt32:BN_LLONG ${x86_gcc_des} ${x86_gcc_opts} EXPORT_VAR_AS_FN:${x86_asm}:coff:win32:cygwin-shared:-D_WINDLL -DOPENSSL_USE_APPLINK:-mno-cygwin:.dll.a",'
   
   and replace it with:
   
   '"mingw", "gcc:-mno-cygwin -DL_ENDIAN -DWIN32_LEAN_AND_MEAN -fomit-frame-pointer -O3 -march=i486 -Wall::-D_MT:MINGW32:-lws2_32 -lgdi32 -lcrypt32:BN_LLONG ${x86_gcc_des} ${x86_gcc_opts} EXPORT_VAR_AS_FN:${x86_asm}:coff:win32:cygwin-shared:-D_WINDLL -DOPENSSL_USE_APPLINK:-mno-cygwin -Wl,--export-all -shared:.dll.a",'
   
   in short, add ' -Wl,--export-all -shared' between '-mno-cygwin' and
   ':.dll.a",'. I got the idea for this from
   http://wagner.pp.ru/~vitus/articles/openssl-mingw.html - thanks!

 - build & install openssl. This is relatively easy, but takes a while.
   Do not attempt to pass a -j flag to make: That might randomly break
   the build. The ./config flags are just a suggestion, these worked for
   me.
   
   $ ./config -shared -no-man -no-idea -no-rc5 -no-mdc2
   $ make depend
   $ make
   $ make install

 - Copy the DLLs that got created into a system directory, so they are
   actually found when needed:
   
   $ cp /usr/local/ssl/bin/*.dll /c/WINDOWS/system32/

 - build and install libevent:
   
   $ ./autogen.sh
   Run the above only if you don't build from a tarball
   
   $ export CPATH=/usr/local/ssl/include:/usr/local/include
   $ export LPATH=/usr/local/lib:/usr/local/ssl/lib
   $ ./configure --enable-gcc-warnings
   $ make
   $ make verify
   $ make install

 - build and test tor:
 
   $ ./autogen.sh
   Run the above only if you don't build from a tarball

   $ ./configure --enable-gcc-warnings --enable-bufferevents \
     --enable-static-libevent --with-libevent-dir=/usr/local/ \
     --with-zlib-dir=/usr/local/ \
     --with-openssl-dir=/usr/local/ssl/
   $ make
   $ make test