vl: trim includes

vl: trim includes

Over time, lots of stuff moved from vl.c into separate
files.  But include statements has never been cleaned,
and they continue to carry lots of anymore-unused stuff.

Remove includes which are not relevant for vl.c anymore.
Apparently there are more includes like this, because
many are included from qemu-common.h and the like, or,
for example, I don't see were we use win32-specific
stuff in vl.c (so that maybe #include <windows.h> might
be removed too).

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>