mingw: bump the minimum Windows version to Vista

Quite some time ago, a last plea to the XP users out there who want to
see Windows XP support in Git for Windows, asking them to get engaged
and help, vanished into the depths of the universe.

We tried for a long time to play nice with the last remaining XP users
who somehow manage to build Git from source, but a recent update of
mingw-w64 (7.0.0.5233.e0c09544 -> 7.0.0.5245.edf66197) finally dropped
the last sign of XP support, and Git for Windows' SDK is no longer able
to build core Git's `master` branch as a consequence. (Git for Windows'
`master` branch already bumped the minimum Windows version to Vista a
while ago, so it is fine.)

It is time to require Windows Vista or later to build Git from source.
This, incidentally, lets us use quite a few nice new APIs.

It also means that we no longer need the inet_pton() and inet_ntop()
emulation, which is nice.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.mak.uname

@@ -381,8 +381,6 @@ ifeq ($(uname_S),Windows)
 	NO_PYTHON = YesPlease
 	BLK_SHA1 = YesPlease
 	ETAGS_TARGET = ETAGS
-	NO_INET_PTON = YesPlease
-	NO_INET_NTOP = YesPlease
 	NO_POSIX_GOODIES = UnfortunatelyYes
 	NATIVE_CRLF = YesPlease
 	DEFAULT_HELP_FORMAT = html
@@ -529,8 +527,6 @@ ifneq (,$(findstring MINGW,$(uname_S)))
 	NO_REGEX = YesPlease
 	NO_PYTHON = YesPlease
 	ETAGS_TARGET = ETAGS
-	NO_INET_PTON = YesPlease
-	NO_INET_NTOP = YesPlease
 	NO_POSIX_GOODIES = UnfortunatelyYes
 	DEFAULT_HELP_FORMAT = html
 	COMPAT_CFLAGS += -DNOGDI -Icompat -Icompat/win32

git-compat-util.h

@@ -147,7 +147,7 @@
 
 #if defined(WIN32) && !defined(__CYGWIN__) /* Both MinGW and MSVC */
 # if !defined(_WIN32_WINNT)
-#  define _WIN32_WINNT 0x0502
+#  define _WIN32_WINNT 0x0600
 # endif
 #define WIN32_LEAN_AND_MEAN  /* stops windows.h including winsock.h */
 #include <winsock2.h>