complibs/ppl: fix 0.11-0.11.2 to compile with --disable-shared

PPL 0.11 (through 0.11.2) had a small bug where it still tried to build
and test its Java interface even when shared libraries are disabled.
Since that's exactly what ct-ng does, it explodes.

This is the patch from the PPL authors (see final link below).

More information can be found in these messages/threads:

Anthony's initial report and analysis with Yann:
http://www.cygwin.com/ml/crossgcc/2011-05/msg00046.html

Ron Flory hit the same problem:
http://www.cygwin.com/ml/crossgcc/2011-05/msg00054.html

Anthony's report to the ppl-devel list:
http://www.cs.unipr.it/pipermail/ppl-devel/2011-May/017450.html

Roberto's reply with a link to the fix in the PPL git repo:
http://www.cs.unipr.it/pipermail/ppl-devel/2011-May/017455.html

Signed-Off-By: Anthony Foiani <anthony.foiani@gmail.com>
(transplanted from 139b85d70b623e51f7585e7c64ecb8c6a6cf4567)

Dmitry V. Levin [Tue, 3 Nov 2009 16:49:49 +0000]

Fix check for linux/netlink.h on Linux 2.6.32-rc5+

* configure.ac (AC_CHECK_HEADERS): In check for linux/netlink.h, include 

  sys/socket.h instead of linux/socket.h beforehand.

diff --git a/configure.ac b/configure.ac

--- a/configure.ac

+++ b/configure.ac

@@ -258,7 +258,7 @@ AC_CHECK_HEADERS([ \

 ], [], [])

 AC_CHECK_HEADERS([linux/icmp.h linux/in6.h linux/netlink.h linux/if_packet.h],

                  [], [], [#include <stddef.h>

-#include <linux/socket.h>])

+#include <sys/socket.h>])

 AC_CHECK_HEADERS([asm/sigcontext.h], [], [], [#include <signal.h>])

 AC_CHECK_TYPES([struct sigcontext_struct,

 		struct sigcontext],,, [#include <signal.h>])