[PATCH xserver] Fix build on Cygwin by ensuring WIN32 check triggers only on MinGW

[Jon Turney]

The type of fd_mask was changed in Cygwin 2.4.0 headers from 'long' to 'unsigned
long'.  This exposes an existing problem with winauth.c, which includes
Xwindows.h (which includes windows.h, which defines WIN32), before including
osdep.h, which causes the now conflicting definition of fd_mask in osdep.h to be
exposed:

In file included from ../os/osdep.h:198:18: error: conflicting types for ‘fd_mask’
 typedef long int fd_mask;
/usr/include/sys/select.h:46:23: note: previous declaration of ‘fd_mask’ was here
 typedef unsigned long fd_mask;

Adjust the include guards in osdep.h to make sure we only use WIN32 guarded code
when not compiling for Cygwin (i.e. WIN32 && !__CYGWIN__)

This isn't a very elegant, but unfortunately appears to be the best solution,
since it doesn't seem to be possible to write the test in a positive form.

Future work: Should also audit of all the other uses of WIN32 in xserver, and
make sure they are correct.

Signed-off-by: Jon Turney <jon.turney at dronecode.org.uk>
---
 os/osdep.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/os/osdep.h b/os/osdep.h
index 2fbfc48..3dc2daf 100644
--- a/os/osdep.h
+++ b/os/osdep.h
@@ -72,7 +72,7 @@ SOFTWARE.
 #if defined(NOFILE) && !defined(NOFILES_MAX)
 #define OPEN_MAX NOFILE
 #else
-#if !defined(WIN32)
+#if !defined(WIN32) || defined(__CYGWIN__)
 #define OPEN_MAX NOFILES_MAX
 #else
 #define OPEN_MAX 512
@@ -178,7 +178,7 @@ extern fd_set ClientsWriteBlocked;
 extern fd_set OutputPending;
 extern fd_set IgnoredClientsWithInput;
 
-#ifndef WIN32
+#if !defined(WIN32) || defined(__CYGWIN__)
 extern int *ConnectionTranslation;
 #else
 extern int GetConnectionTranslation(int conn);
@@ -193,7 +193,7 @@ extern Bool NumNotifyWriteFd;
 extern WorkQueuePtr workQueue;
 
 /* in WaitFor.c */
-#ifdef WIN32
+#if defined(WIN32) && !defined(__CYGWIN__)
 typedef long int fd_mask;
 #endif
 #define ffs mffs
-- 
2.7.0