[PATCH] Fix IcedTea6 build.

[Ricardo Wurmus]

When the new RUNPATH validation phase was enabled by default, GCJ could
no longer be built.  After the GCJ build was fixed I noticed that
IcedTea6 failed because it could no longer find "gcj/libgcj-config.h".
I do not know what commit actually caused this failure.

A fix is attached.  The patch adds the target-dependent GCJ include
directory (whose "gcj" directory contains nothing more than
"libgcj-config.h") to the CPATH, so that the header file can be found at
build time.

>From c4888d11730061d73a7a242099999d35d4ad5c0f Mon Sep 17 00:00:00 2001
From: Ricardo Wurmus <address@hidden>
Date: Mon, 11 May 2015 15:50:34 +0200
Subject: [PATCH] gnu: icedtea6: Add target-dependent include directory to
 CPATH.

* gnu/packages/java.scm (gcj-4.8)[arguments]: Add target-dependent GCJ include
  directory to CPATH environment variable.
---
 gnu/packages/java.scm | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/gnu/packages/java.scm b/gnu/packages/java.scm
index 2a56769..182ada6 100644
--- a/gnu/packages/java.scm
+++ b/gnu/packages/java.scm
@@ -459,11 +459,19 @@ build process and its dependencies, whereas Make uses 
Makefile format.")
           (alist-cons-before
            'configure 'set-additional-paths
            (lambda* (#:key inputs #:allow-other-keys)
+             (use-modules (ice-9 popen))
+             (use-modules (ice-9 rdelim))
              (let* ((gcjdir  (assoc-ref %build-inputs "gcj"))
                     (gcjlib  (string-append gcjdir "/lib"))
-                    (antpath (string-append (getcwd) "/../apache-ant-1.9.4")))
+                    (antpath (string-append (getcwd) "/../apache-ant-1.9.4"))
+                    ;; Get target-specific include directory
+                    (gcjinclude (let* ((port (open-input-pipe "gcj 
-print-file-name=include"))
+                                       (str  (read-line port)))
+                                  (close-pipe port)
+                                  str)))
                (setenv "CPATH"
-                       (string-append (assoc-ref %build-inputs "libxrender")
+                       (string-append gcjinclude ":"
+                                      (assoc-ref %build-inputs "libxrender")
                                       "/include/X11/extensions" ":"
                                       (assoc-ref %build-inputs "libxtst")
                                       "/include/X11/extensions" ":"
-- 
2.1.0