gnu: Move cflow, Complexity, and GLOBAL to (gnu packages code).

* gnu/packages/code.scm (cflow, complexity, global): New variables.
* gnu/packages/cflow.scm, gnu/packages/complexity.scm,
  gnu/packages/global.scm: Remove.
* gnu-system.am (GNU_SYSTEM_MODULES): Adjust accordingly.

gnu/packages/code.scm

@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2015 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013, 2015 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2015 Andreas Enge <andreas@enge.fr>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -21,10 +22,105 @@
   #:use-module (guix download)
   #:use-module (guix licenses)
   #:use-module (guix build-system gnu)
-  #:use-module (gnu packages perl))
+  #:use-module (gnu packages emacs)
+  #:use-module (gnu packages perl)
+  #:use-module (gnu packages texinfo)
+  #:use-module (gnu packages autogen)
+  #:use-module (gnu packages ncurses)
+  #:use-module (gnu packages autotools))
 
 ;;; Tools to deal with source code: metrics, cross-references, etc.
 
+(define-public cflow
+  (package
+    (name "cflow")
+    (version "1.4")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "mirror://gnu/cflow/cflow-"
+                                  version ".tar.bz2"))
+              (sha256
+               (base32
+                "1jkbq97ajcf834z68hbn3xfhiz921zhn39gklml1racf0kb3jzh3"))))
+    (build-system gnu-build-system)
+
+    ;; Needed to have cflow-mode.el installed.
+    (native-inputs `(("emacs" ,emacs)))
+
+    (home-page "http://www.gnu.org/software/cflow/")
+    (synopsis "Create a graph of control flow within a program")
+    (description
+     "GNU cflow analyzes C source files and produces a graph charting the
+control flow of the program.  It can output the graph in several styles and
+in either the POSIX format or in an extended GNU format. cflow also includes
+a major mode for Emacs for examining the flowcharts that it produces.")
+    (license gpl3+)))
+
+(define-public complexity
+  (package
+    (name "complexity")
+    (version "1.2")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "mirror://gnu/complexity/complexity-"
+                                  version ".tar.gz"))
+              (sha256
+               (base32
+                "0pmlhlj1chl4caaqffvn1cy9z8gwmjbx97syi7pdfa0vqygkql6d"))))
+    (build-system gnu-build-system)
+    (native-inputs
+     `(("texinfo" ,texinfo)
+       ("autogen" ,autogen)))
+    (home-page "http://www.gnu.org/software/complexity/")
+    (synopsis "Analyze complexity of C functions")
+    (description
+     "GNU complexity provides tools for finding procedures that are
+convoluted, overly long or otherwise difficult to understand.  This
+may help in learning or reviewing unfamiliar code or perhaps
+highlighting your own code that seemed comprehensible when you wrote it.")
+    (license gpl3+)))
+
+(define-public global                             ; a global variable
+  (package
+    (name "global")
+    (version "6.3.4")
+    (source (origin
+             (method url-fetch)
+             (uri (string-append "mirror://gnu/global/global-"
+                                 version ".tar.gz"))
+             (sha256
+              (base32
+               "0hcplcayyjf42d8ygzla6142b5dq4ybq4wg3n3cgx3b5yfhvic85"))))
+    (build-system gnu-build-system)
+    (inputs `(("ncurses" ,ncurses)
+              ("libltdl" ,libltdl)))
+    (arguments
+     `(#:configure-flags
+       (list (string-append "--with-ncurses="
+                            (assoc-ref %build-inputs "ncurses")))
+
+       #:phases (alist-cons-after
+                 'install 'post-install
+                 (lambda* (#:key outputs #:allow-other-keys)
+                   ;; Install the Emacs Lisp file in the right place.
+                   (let* ((out  (assoc-ref outputs "out"))
+                          (data (string-append out "/share/gtags"))
+                          (lisp (string-append out "/share/emacs/site-lisp")))
+                     (mkdir-p lisp)
+                     (copy-file (string-append data "/gtags.el")
+                                (string-append lisp "/gtags.el"))
+                     (delete-file (string-append data "/gtags.el"))
+                     #t))
+                 %standard-phases)))
+    (home-page "http://www.gnu.org/software/global/")
+    (synopsis "Cross-environment source code tag system")
+    (description
+     "GLOBAL is a source code tagging system that functions in the same way
+across a wide array of environments, such as different text editors, shells
+and web browsers.  The resulting tags are useful for quickly moving around in
+a large, deeply nested project.")
+    (license gpl3+)))
+
 (define-public sloccount
   (package
     (name "sloccount")