Remove broken MSVC support

MSVC compilation has been broken since at least 1e417b7275 ("All remaining
files in src/common belong to the event loop.") deleted
src/common/Makefile.nmake in 2018.

doc/building-tor-msvc.txt

@@ -1,122 +0,0 @@
-Building Tor with MSVC.
-=======================
-
-NOTE: This is not the preferred method for building Tor on windows: we use
-mingw for our packages.
-
-Last updated 9 September 2014.
-
-
-Requirements:
--------------
-
- * Visual Studio 2010
-    https://go.microsoft.com/fwlink/?LinkId=323467
- * CMake 2.8.12.2
-    https://www.cmake.org/download/
- * Perl 5.16
-    https://www.activestate.com/activeperl/downloads
- * Latest stable OpenSSL tarball
-    https://www.openssl.org/source/
- * Latest stable zlib tarball
-    https://zlib.net/
- * Latest stable libevent Libevent tarball
-    https://github.com/libevent/libevent/releases
-
-Make sure you check signatures for all these packages.
-
-Steps:
-------
-
-Building OpenSSL from source as a shared library:
-
- cd <openssl source dir>
- perl Configure VC-WIN32
- perl util\mkfiles.pl >MINFO
- perl util\mk1mf.pl no-asm dll VC-WIN32 >32dll.mak
- perl util\mkdef.pl 32 libeay > ms\libeay32.def
- perl util\mkdef.pl 32 ssleay > ms\ssleay32.def
- nmake -f 32dll.mak
-
-Making OpenSSL final package:
-
- Create <openssl final package dir>, I'd recommend using a name like <openssl
- source dir>-vc10.
-
- Copy the following directories and files to their respective locations
-  <openssl source dir>\inc32\openssl => <openssl final package dir>\include\openssl
-  <openssl source dir>\out32dll\libeay32.lib => <openssl final package dir>\lib\libeay32.lib
-  <openssl source dir>\out32dll\ssleay32.lib => <openssl final package dir>\lib\ssleay32.lib
-  <openssl source dir>\out32dll\libeay32.dll => <openssl final package dir>\bin\libeay32.dll
-  <openssl source dir>\out32dll\openssl.exe => <openssl final package dir>\bin\openssl.exe
-  <openssl source dir>\out32dll\ssleay32.dll => <openssl final package dir>\bin\ssleay32.dll
-
-Building Zlib from source:
-
- cd <zlib source dir>
- nmake -f win32/Makefile.msc
-
-Building libevent:
-
- cd <libevent source dir>
- mkdir build && cd build
- SET OPENSSL_ROOT_DIR=<openssl final package dir>
- cmake -G "NMake Makefiles" .. -DCMAKE_BUILD_TYPE:STRING=RelWithDebInfo -DCMAKE_C_FLAGS_RELWITHDEBINFO:STRING="/MT /Zi /O2 /Ob1 /D NDEBUG" -DZLIB_LIBRARY:FILEPATH="<zlib source dir>\zdll.lib" -DZLIB_INCLUDE_DIR:PATH="<zlib source dir>"
- nmake event
-
-Building Tor:
-
- Create a dir above tor source dir named build-alpha and two subdirs include
- and lib.
-
- Your build tree should now be similar to this one:
-  * build-alpha
-    - include
-    - lib
-  * <libevent source dir>
-    - build
-    - cmake
-    - ...
-  * <openssl source dir>
-    - ...
-    - ms
-    - util
-    - ...
-  * <openssl final package dir>
-    - bin
-    - include
-    - lib
-  * <tor source dir>
-    - ...
-    - src
-    - ...
-  * <zlib source dir>
-    - ...
-    - win32
-    - ...
-
- Copy the following dirs and files to the following locations:
-  <openssl final package dir>\include\openssl => build-alpha\include\openssl
-  <libevent source dir>\include => build-alpha\include
-  <libevent source dir>\WIN32-Code\nmake\event2 => build-alpha\include\event2
-  <zlib source dir>\z*.h => build-alpha\include\z*.h
-
- Now copy the following files to the following locations and rename them
- according new names:
-
-  <libevent source dir>\build\lib\event.lib => build-alpha\lib\libevent.lib
-  <openssl final package dir>\lib\libeay32.lib => build-alpha\lib\libcrypto.lib
-  <openssl final package dir>\lib\ssleay32.lib => build-alpha\lib\libssl.lib
-  <zlib source dir>\zdll.lib => build-alpha\lib\libz.lib
-
- And we are now ready for the build process:
-
-  cd <tor source dir>
-  nmake -f Makefile.nmake
-
- After the above process is completed there should be a tor.exe in <tor
- source dir>\src\or
-
- Copy tor.exe to desired location and also copy zlib1.dll, libeay32.dll and
- ssleay32.dll from built zlib and openssl packages
-