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)

--- gcc-4.2.1-stock/gcc/config/alpha/linux-unwind.h	2005-06-24 20:22:41.000000000 -0500

+++ gcc-4.2.1/gcc/config/alpha/linux-unwind.h	2007-09-01 20:21:34.000000000 -0500

@@ -29,6 +29,9 @@ Boston, MA 02110-1301, USA.  */

 /* Do code reading to identify a signal frame, and set the frame

    state data appropriately.  See unwind-dw2.c for the structs.  */

+/* Don't use this if inhibit_libc is set

+   The build for this target will fail trying to include missing headers */

+#ifndef inhibit_libc

 #include <signal.h>

 #include <sys/ucontext.h>

@@ -80,3 +83,4 @@ alpha_fallback_frame_state (struct _Unwi

   fs->retaddr_column = 64;

   return _URC_NO_REASON;

 }

+#endif /* inhibit_libc */