On MS-Windows, define _WIN32_WINNT in a single common place.

This changeset defines _WIN32_WINNT to at least 0x0501, the level
of Windows XP, unless defined to a higher level, in a single
place.  It then removes all the overrides of _WIN32_WINNT in
individual files as no longer needed.  Doing this also solves
compilation of windows-nat.c with mingw.org's MinGW, as that
file uses CONSOLE_FONT_INFO which needs the XP level to become
exposed in the Windows headers, while mingw.org defaults to
Windows 9X.

gdb/ChangeLog:
2019-05-03  Eli Zaretskii  <eliz@gnu.org>

	* common/common-defs.h [__MINGW32__ || __CYGWIN__]: Define
	_WIN32_WINNT to the XP level, unless already defined to a higher
	level.

	* unittests/parse-connection-spec-selftests.c:
	* ser-tcp.c:
	* common/netstuff.c [USE_WIN32API]:  Remove the _WIN32_WINNT
	override.

gdb/gdbserver/ChangeLog:
2019-05-03  Eli Zaretskii  <eliz@gnu.org>

	* remote-utils.c:
	* gdbreplay.c [USE_WIN32API]: Remove the _WIN32_WINNT override.

8 files changed, 28 insertions, 20 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index efe07af..4820ebf 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,14 @@
 2019-05-03  Eli Zaretskii  <eliz@gnu.org>
 
+	* common/common-defs.h [__MINGW32__ || __CYGWIN__]: Define
+	_WIN32_WINNT to the XP level, unless already defined to a higher
+	level.
+
+	* unittests/parse-connection-spec-selftests.c:
+	* ser-tcp.c:
+	* common/netstuff.c [USE_WIN32API]:  Remove the _WIN32_WINNT
+	override.
+
 	* symfile.c (find_separate_debug_file): Remove colon from the
 	drive spec of DOS/Windows file names of the target, so that the
 	file name produced from DEBUGDIR and the target's directory will
diff --git a/gdb/common/common-defs.h b/gdb/common/common-defs.h
index 6b1f004..8c16492 100644
--- a/gdb/common/common-defs.h
+++ b/gdb/common/common-defs.h
@@ -72,6 +72,20 @@
 #define _FORTIFY_SOURCE 2
 #endif
 
+/* We don't support Windows versions before XP, so we define
+   _WIN32_WINNT correspondingly to ensure the Windows API headers
+   expose the required symbols.  */
+#if defined (__MINGW32__) || defined (__CYGWIN__)
+# ifdef _WIN32_WINNT
+#  if _WIN32_WINNT < 0x0501
+#   undef _WIN32_WINNT
+#   define _WIN32_WINNT 0x0501
+#  endif
+# else
+#  define _WIN32_WINNT 0x0501
+# endif
+#endif	/* __MINGW32__ || __CYGWIN__ */
+
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/gdb/common/netstuff.c b/gdb/common/netstuff.c
index 27fdc73..b192de7 100644
--- a/gdb/common/netstuff.c
+++ b/gdb/common/netstuff.c
@@ -21,10 +21,6 @@
 #include <algorithm>
 
 #ifdef USE_WIN32API
-#if _WIN32_WINNT < 0x0501
-# undef _WIN32_WINNT
-# define _WIN32_WINNT 0x0501
-#endif
 #include <ws2tcpip.h>
 #else
 #include <netinet/in.h>
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 2985281..82278e7 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,8 @@
+2019-05-03  Eli Zaretskii  <eliz@gnu.org>
+
+	* remote-utils.c:
+	* gdbreplay.c [USE_WIN32API]: Remove the _WIN32_WINNT override.
+
 2019-04-19  Tom Tromey  <tom@tromey.com>
 
 	* server.c (struct vstop_notif): Derive from notif_event.
diff --git a/gdb/gdbserver/gdbreplay.c b/gdb/gdbserver/gdbreplay.c
index ca0a9d3..2800e78 100644
--- a/gdb/gdbserver/gdbreplay.c
+++ b/gdb/gdbserver/gdbreplay.c
@@ -45,10 +45,6 @@
 #endif
 
 #if USE_WIN32API
-#if _WIN32_WINNT < 0x0501
-# undef _WIN32_WINNT
-# define _WIN32_WINNT 0x0501
-#endif
 #include <ws2tcpip.h>
 #endif
 
diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
index 903d773..1d27ea3 100644
--- a/gdb/gdbserver/remote-utils.c
+++ b/gdb/gdbserver/remote-utils.c
@@ -63,10 +63,6 @@
 #include <sys/stat.h>
 
 #if USE_WIN32API
-#if _WIN32_WINNT < 0x0501
-# undef _WIN32_WINNT
-# define _WIN32_WINNT 0x0501
-#endif
 #include <ws2tcpip.h>
 #endif
 
diff --git a/gdb/ser-tcp.c b/gdb/ser-tcp.c
index 039b043..927a285 100644
--- a/gdb/ser-tcp.c
+++ b/gdb/ser-tcp.c
@@ -39,10 +39,6 @@
 #include "common/gdb_sys_time.h"
 
 #ifdef USE_WIN32API
-#if _WIN32_WINNT < 0x0501
-# undef _WIN32_WINNT
-# define _WIN32_WINNT 0x0501
-#endif
 #include <ws2tcpip.h>
 #ifndef ETIMEDOUT
 #define ETIMEDOUT WSAETIMEDOUT
diff --git a/gdb/unittests/parse-connection-spec-selftests.c b/gdb/unittests/parse-connection-spec-selftests.c
index a4beb66..915aa66 100644
--- a/gdb/unittests/parse-connection-spec-selftests.c
+++ b/gdb/unittests/parse-connection-spec-selftests.c
@@ -22,10 +22,6 @@
 #include "common/netstuff.h"
 #include "diagnostics.h"
 #ifdef USE_WIN32API
-#if _WIN32_WINNT < 0x0501
-# undef _WIN32_WINNT
-# define _WIN32_WINNT 0x0501
-#endif
 #include <ws2tcpip.h>
 #else
 #include <netinet/in.h>