Include less of the generated modular QAPI headers

In my "build everything" tree, a change to the types in
qapi-schema.json triggers a recompile of about 4800 out of 5100
objects.

The previous commit split up qmp-commands.h, qmp-event.h, qmp-visit.h,
qapi-types.h.  Each of these headers still includes all its shards.
Reduce compile time by including just the shards we actually need.

To illustrate the benefits: adding a type to qapi/migration.json now
recompiles some 2300 instead of 4800 objects.  The next commit will
improve it further.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20180211093607.27351-24-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
[eblake: rebase to master]
Signed-off-by: Eric Blake <eblake@redhat.com>
diff --git a/net/vhost-user.c b/net/vhost-user.c
index d024573..e0f16c8 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -14,10 +14,10 @@
 #include "net/vhost-user.h"
 #include "chardev/char-fe.h"
 #include "qapi/error.h"
+#include "qapi/qapi-commands-net.h"
 #include "qemu/config-file.h"
 #include "qemu/error-report.h"
 #include "qemu/option.h"
-#include "qmp-commands.h"
 #include "trace.h"
 
 typedef struct VhostUserState {