xfree86: common: fix missing include of <errno.h>

It's much cleaner to always include directly what one needs,
instead of relying on very indirect including.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1435>

hw/xfree86/common/xf86Configure.c

@@ -27,6 +27,8 @@
 #include <xorg-config.h>
 #endif
 
+#include <errno.h>
+
 #include "xf86.h"
 #include "xf86Config.h"
 #include "xf86_OSlib.h"

hw/xfree86/common/xf86Events.c

@@ -53,9 +53,11 @@
 #include <xorg-config.h>
 #endif
 
+#include <errno.h>
 #include <X11/X.h>
 #include <X11/Xproto.h>
 #include <X11/Xatom.h>
+
 #include "misc.h"
 #include "xf86.h"
 #include "xf86Priv.h"