gnu: gnu-build-system: Add CC_FOR_BUILD to configure flags.

* guix/build/gnu-build-system.scm: Add new configure flag: CC_FOR_BUILD=gcc

* gnu/packages/gnupg.scm, gnu/packages/guile.scm, gnu/packages/make-bootstrap.scm:
  remove CC_FOR_BUILD from these package descriptions.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/gnupg.scm

@@ -44,10 +44,6 @@
        (base32
         "0pz58vr12qihq2f0bypjxsb6cf6ajq5258fmfm8s6lvwm3b9xz6a"))))
     (build-system gnu-build-system)
-    (arguments
-     (if (%current-target-system)
-         '(#:configure-flags '("CC_FOR_BUILD=gcc"))
-         '()))
     (home-page "http://gnupg.org")
     (synopsis
      "Libgpg-error, a small library that defines common error values for all GnuPG components")

gnu/packages/guile.scm

@@ -150,11 +150,7 @@ without requiring the source code to be rewritten.")
                     (substitute* "module/ice-9/popen.scm"
                       (("/bin/sh")
                        (string-append bash "/bin/bash")))))
-                %standard-phases)
-
-      ,@(if (%current-target-system)
-            '(#:configure-flags '("CC_FOR_BUILD=gcc"))
-            '())))
+                %standard-phases)))
 
    (native-search-paths
     (list (search-path-specification

gnu/packages/make-bootstrap.scm

@@ -502,10 +502,7 @@ for `sh' in $PATH, and without nscd, and with static NSS modules."
                    `(;; When `configure' checks for ltdl availability, it
                      ;; doesn't try to link using libtool, and thus fails
                      ;; because of a missing -ldl.  Work around that.
-                     #:configure-flags '("LDFLAGS=-ldl"
-                                         ,@(if (%current-target-system)
-                                               '("CC_FOR_BUILD=gcc")
-                                               '()))
+                     #:configure-flags '("LDFLAGS=-ldl")
 
                      #:phases (alist-cons-before
                                'configure 'static-guile

guix/build/gnu-build-system.scm

@@ -136,7 +136,10 @@ makefiles."
          (bash       (or (and=> (assoc-ref (or native-inputs inputs) "bash")
                                 (cut string-append <> "/bin/bash"))
                          "/bin/sh"))
-         (flags      `(,(string-append "CONFIG_SHELL=" bash)
+         (flags      `(,@(if target             ; cross building
+                             '("CC_FOR_BUILD=gcc")
+                             '())
+                       ,(string-append "CONFIG_SHELL=" bash)
                        ,(string-append "SHELL=" bash)
                        ,(string-append "--prefix=" prefix)
                        "--enable-fast-install"    ; when using Libtool