Fix straggling MS_WINDOWS issues; add a changes file

There was one MS_WINDOWS that remained because it wasn't on a macro
line; a few remaining uses (and the definition!) in configure.in;
and a now-nonsensical stanza of eventdns_tor.h that previously
defined 'WIN32' if it didn't exist.

changes/win32macro

@@ -0,0 +1,4 @@
+  o Code simplifications and refactoring:
+    - Use the _WIN32 macro throughout our code to detect Windows.
+      (Previously we had used the obsolete 'WIN32' and the
+      idiosyncratic 'MS_WINDOWS'.)

configure.in

@@ -257,9 +257,6 @@ bwin32=true; AC_MSG_RESULT([yes]),
 bwin32=false; AC_MSG_RESULT([no]))
 fi
 
-if test "$bwin32" = true; then
-AC_DEFINE(MS_WINDOWS, 1, [Define to 1 if we are building for Windows.])
-fi
 AM_CONDITIONAL(BUILD_NT_SERVICES, test x$bwin32 = xtrue)
 
 dnl Enable C99 when compiling with MIPSpro
@@ -573,7 +570,7 @@ if test "$natpmp" = "true"; then
     AC_DEFINE(NAT_PMP, 1, [Define to 1 if we are building with nat-pmp.])
     TOR_SEARCH_LIBRARY(libnatpmp, $trylibnatpmpdir, [-lnatpmp $TOR_LIB_WS32 $TOR_LIB_IPHLPAPI],
         [#include <natpmp.h>],
-        [#ifdef MS_WINDOWS
+        [#ifdef _WIN32
          #define STATICLIB
          #endif
          #include <natpmp.h>],
@@ -772,7 +769,7 @@ AC_CHECK_TYPES([struct in6_addr, struct sockaddr_in6, sa_family_t], , ,
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define WIN32_WINNT 0x400
 #define _WIN32_WINNT 0x400
 #define WIN32_LEAN_AND_MEAN
@@ -797,7 +794,7 @@ AC_CHECK_MEMBERS([struct in6_addr.s6_addr32, struct in6_addr.s6_addr16, struct s
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define WIN32_WINNT 0x400
 #define _WIN32_WINNT 0x400
 #define WIN32_LEAN_AND_MEAN

src/common/util.c

@@ -2972,7 +2972,7 @@ finish_daemon(const char *desired_cwd)
   close(daemon_filedes[1]);
 }
 #else
-/* defined(MS_WINDOWS) */
+/* defined(_WIN32) */
 void
 start_daemon(void)
 {

src/or/eventdns_tor.h

@@ -14,11 +14,6 @@ typedef unsigned char u_char;
 #endif
 #include "torint.h"
 
-#if defined(_WIN32) && !defined(_WIN32)
-/* How did _this_ happen? */
-#define _WIN32
-#endif
-
 /* These are for debugging possible memory leaks. */
 #include "util.h"
 #include "compat.h"