gnu: gcc: Use the system zlib.

* gnu/packages/gcc.scm (gcc-4.7) <configure-flags>: Pass
'--with-system-zlib'.
* gnu/packages/commencement.scm (gcc-boot0)[arguments]: Remove
'--with-system-zlib' from the configure flags.
* gnu/packages/commencement.scm (zlib-final): New variable.
(gcc-final)[arguments]: Add ZLIB-FINAL to #:allowed-references.
Pass -L and -Wl,-rpath for zlib in LDFLAGS, as a configure flag.
[inputs]: Add LD-WRAPPER-BOOT3 and ZLIB-FINAL.

gnu/packages/commencement.scm

@@ -204,7 +204,8 @@ (define gcc-boot0
                             "--disable-libssp"
                             "--disable-libquadmath"
                             "--disable-decimal-float")
-                      (remove (cut string-match "--enable-languages.*" <>)
+                      (remove (cut string-match
+                                "--(with-system-zlib|enable-languages.*)" <>)
                               ,flags)))
             ((#:phases phases)
              `(alist-cons-after
@@ -548,6 +549,25 @@ (define libstdc++
      (propagated-inputs '())
      (synopsis "GNU C++ standard library (intermediate)"))))
 
+(define zlib-final
+  ;; Zlib used by GCC-FINAL.
+  (package-with-bootstrap-guile
+   (package
+     (inherit zlib)
+     (arguments
+      `(#:guile ,%bootstrap-guile
+        #:implicit-inputs? #f
+        #:allowed-references ("out" ,glibc-final)
+        ,@(package-arguments zlib)))
+     (inputs %boot2-inputs))))
+
+(define ld-wrapper-boot3
+  ;; A linker wrapper that uses the bootstrap Guile.
+  (make-ld-wrapper "ld-wrapper-boot3"
+                   #:binutils binutils-final
+                   #:guile %bootstrap-guile
+                   #:bash (car (assoc-ref %boot2-inputs "bash"))))
+
 (define gcc-final
   ;; The final GCC.
   (package (inherit gcc-boot0)
@@ -562,7 +582,7 @@ (define gcc-final
      `(#:guile ,%bootstrap-guile
        #:implicit-inputs? #f
 
-       #:allowed-references ("out" "lib"
+       #:allowed-references ("out" "lib" ,zlib-final
                              ,glibc-final ,static-bash-for-glibc)
 
        ;; Things like libasan.so and libstdc++.so NEED ld.so for some
@@ -583,13 +603,15 @@ (define gcc-final
                  (loop rest)))))
            ((#:make-flags flags)
             ;; Since $LIBRARY_PATH is not honored, add the relevant flags.
-            `(map (lambda (flag)
+            `(let ((zlib (assoc-ref %build-inputs "zlib")))
+               (map (lambda (flag)
                       (if (string-prefix? "LDFLAGS=" flag)
                           (string-append flag " -L"
                                          (assoc-ref %build-inputs "libstdc++")
-                                       "/lib")
+                                         "/lib -L" zlib "/lib -Wl,-rpath="
+                                         zlib "/lib")
                           flag))
-                  ,flags))
+                    ,flags)))
            ((#:phases phases)
             `(alist-delete 'symlink-libgcc_eh ,phases)))))
 
@@ -604,17 +626,12 @@ (define gcc-final
     (inputs `(("gmp-source" ,(bootstrap-origin (package-source gmp)))
               ("mpfr-source" ,(package-source mpfr))
               ("mpc-source" ,(package-source mpc))
+              ("ld-wrapper" ,ld-wrapper-boot3)
               ("binutils" ,binutils-final)
               ("libstdc++" ,libstdc++)
+              ("zlib" ,zlib-final)
               ,@%boot2-inputs))))
 
-(define ld-wrapper-boot3
-  ;; A linker wrapper that uses the bootstrap Guile.
-  (make-ld-wrapper "ld-wrapper-boot3"
-                   #:binutils binutils-final
-                   #:guile %bootstrap-guile
-                   #:bash (car (assoc-ref %boot2-inputs "bash"))))
-
 (define %boot3-inputs
   ;; 4th stage inputs.
   `(("gcc" ,gcc-final)

gnu/packages/gcc.scm

@@ -97,6 +97,7 @@ (define-public gcc-4.7
                    '("--enable-plugin"
                      "--enable-languages=c,c++"
                      "--disable-multilib"
+                     "--with-system-zlib"
 
                      ;; No pre-compiled libstdc++ headers, to save space.
                      "--disable-libstdcxx-pch"