qemu-doc: Add missing "@c man end" statements

qemu-doc: Add missing "@c man end" statements

Since commit 3f2ce724f1f1 ("Move the qemu-ga description into a
separate chapter"), the qemu.1 man page looks pretty much screwed
up, e.g. the title was "qemu-ga - QEMU Guest Agent" instead of
"qemu-doc - QEMU Emulator User Documentation". However, that movement
of the gemu-ga chapter is not the real problem, it just triggered
another bug in the qemu-doc.texi: There are some parts in the file
which introduce a "@c man begin OPTIONS" section, but never close
it again with "@c man end". After adding the proper end tags here,
the title of the man page is right again and the previously wrongly
tagged sections now also show up correctly in the man page, too.

Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1497863771-24929-1-git-send-email-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>