meson: remove obsolete check for linux/magic.h

The linux/magic.h header has existed since

  commit e18fa700c9a31360bc8f193aa543b7ef7b39a06b
  Author: Jeff Garzik <jeff@garzik.org>
  Date:   Sun Sep 24 11:13:19 2006 -0400

    Move several *_SUPER_MAGIC symbols to include/linux/magic.h.

This is old enough that all our supported platforms can be assumed
to have this header.

Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

meson.build

@@ -596,7 +596,6 @@ headers = [
   'ifaddrs.h',
   'libtasn1.h',
   'linux/kvm.h',
-  'linux/magic.h',
   'mntent.h',
   'net/ethernet.h',
   'net/if.h',

src/util/virfile.c

@@ -62,9 +62,7 @@
 #include <sys/file.h>
 
 #ifdef __linux__
-# if WITH_LINUX_MAGIC_H
 # include <linux/magic.h>
-# endif
 # include <sys/statfs.h>
 # include <linux/loop.h>
 # include <sys/ioctl.h>

tests/securityselinuxhelper.c

@@ -23,9 +23,7 @@
  * detected. */
 
 #include "virmock.h"
-#if WITH_LINUX_MAGIC_H
-# include <linux/magic.h>
-#endif
+#include <linux/magic.h>
 #include <selinux/selinux.h>
 #include <selinux/label.h>
 #include <sys/vfs.h>

tests/virfilemock.c

@@ -21,7 +21,7 @@
 #include <stdio.h>
 #include <mntent.h>
 #include <sys/vfs.h>
-#if WITH_LINUX_MAGIC_H
+#ifdef __linux__
 # include <linux/magic.h>
 #endif