zink: put sysmacros.h include under #ifdef MAJOR_IN_SYSMACROS

Fixes the build on OpenBSD, where major() is in sys/types and
sys/sysmacros.h does not exist.  Also include sys/mkdev.h if
MAJOR_IN_MKDEV is defined.

Fixes: 6d60115be7 ("zink: Fix enumerate devices when running compositor")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26735>

src/gallium/drivers/zink/zink_screen.c

@@ -55,8 +55,13 @@
 #include <xf86drm.h>
 #include <fcntl.h>
 #include <sys/stat.h>
+#ifdef MAJOR_IN_MKDEV
+#include <sys/mkdev.h>
+#endif
+#ifdef MAJOR_IN_SYSMACROS
 #include <sys/sysmacros.h>
 #endif
+#endif
 
 static int num_screens = 0;
 bool zink_tracing = false;