page-server: allow to execute page-server in the background (v2)

page-server creates a listen socket and only then goes into the
background, so we can be sure, that page-server is ready for work after
detaching.

v2: call daemon() in a proper place and reuse the option -d

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
make: Add scripts/utilities.mak

Some features need to be tested on the system
where the project is compiled, so instead of
drowning into autoconf hell lets try to handle
all this with make facility.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
make: Introduce compile time include/config.h generation

It's being reported that some systems (as Ubuntu 13.04) already
have struct tcp_repair_opt definition in their system headers.

| sk-tcp.c:25:8: error: redefinition of struct tcp_repair_opt
| sk-tcp.c:31:2: error: redeclaration of enumerator TCP_NO_QUEUE

So add a facility for compile time testing for reported entities
to be present on a system. For this we generate include/config.h
where all tested entries will lay and source code need to include
it only in places where really needed.

Reported-by: Vasily Averin <vvs@parallels.com>
Acked-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>