meson: fix meson 0.58 warning with libvhost-user subproject

Meson now checks that subprojects do not access files from parent
project. While we all agree this is best practice, libvhost-user also
want to share a few headers with QEMU, and libvhost-user isn't really a
standalone project at this point (although this is making the dependency
a bit more explicit).

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210505151313.203258-1-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

subprojects/libvhost-user/include/atomic.h

@@ -0,0 +1 @@
+../../../include/qemu/atomic.h

subprojects/libvhost-user/libvhost-user.c

@@ -40,7 +40,7 @@
 
 #endif
 
-#include "qemu/atomic.h"
+#include "include/atomic.h"
 
 #include "libvhost-user.h"
 

subprojects/libvhost-user/meson.build

@@ -4,21 +4,17 @@ project('libvhost-user', 'c',
 
 threads = dependency('threads')
 glib = dependency('glib-2.0')
-inc = include_directories('../../include', '../../linux-headers')
 
 vhost_user = static_library('vhost-user',
                             files('libvhost-user.c'),
-                            include_directories: inc,
                             dependencies: threads,
                             c_args: '-D_GNU_SOURCE')
 
 executable('link-test', files('link-test.c'),
-           link_whole: vhost_user,
-           include_directories: inc)
+           link_whole: vhost_user)
 
 vhost_user_glib = static_library('vhost-user-glib',
                                  files('libvhost-user-glib.c'),
-                                 include_directories: inc,
                                  link_with: vhost_user,
                                  dependencies: glib)
 

subprojects/libvhost-user/standard-headers/linux

@@ -0,0 +1 @@
+../../../include/standard-headers/linux