distro: Add Flex.

* distro/packages/flex.scm,
  distro/packages/patches/flex-bison-tests.patch: New files.
* Makefile.am (MODULES): Add `flex.scm'.
  (dist_patch_DATA): Add `flex-bison-tests.patch'.

Makefile.am

@@ -48,6 +48,7 @@ MODULES =					\
   distro/packages/bootstrap.scm			\
   distro/packages/compression.scm		\
   distro/packages/ed.scm			\
+  distro/packages/flex.scm			\
   distro/packages/gawk.scm			\
   distro/packages/gdbm.scm			\
   distro/packages/gnupg.scm			\
@@ -84,6 +85,7 @@ patchdir = $(pkgdatadir)/patches
 dist_patch_DATA =						\
   distro/packages/patches/binutils-ld-new-dtags.patch		\
   distro/packages/patches/diffutils-gets-undeclared.patch	\
+  distro/packages/patches/flex-bison-tests.patch		\
   distro/packages/patches/glibc-no-ld-so-cache.patch		\
   distro/packages/patches/guile-1.8-cpp-4.5.patch		\
   distro/packages/patches/guile-default-utf8.patch		\

distro/packages/flex.scm

@@ -0,0 +1,58 @@
+;;; Guix --- Nix package management from Guile.         -*- coding: utf-8 -*-
+;;; Copyright (C) 2012 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; This file is part of Guix.
+;;;
+;;; Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (distro packages bison)
+  #:use-module (guix packages)
+  #:use-module (guix download)
+  #:use-module (guix build-system gnu)
+  #:use-module (distro)
+  #:use-module (distro packages m4)
+  #:use-module (distro packages bison))
+
+(define-public flex
+  (package
+    (name "flex")
+    (version "2.5.37")
+    (source (origin
+             (method url-fetch)
+             (uri (string-append "mirror://sourceforge/flex/flex-"
+                                 version ".tar.bz2"))
+             (sha256
+              (base32
+               "0ah5mi4j62b85a9rllv1004mzjb5cd0mn4glvz13p88rpx77pahp"))))
+    (build-system gnu-build-system)
+    (arguments
+     '(#:patches (list (assoc-ref %build-inputs "patch/bison-tests"))))
+    (inputs `(("patch/bison-tests" ,(search-patch "flex-bison-tests.patch"))
+              ("bison" ,bison)))
+    (propagated-inputs `(("m4" ,m4)))
+    (home-page "http://flex.sourceforge.net/")
+    (synopsis "A fast lexical analyser generator")
+    (description
+     "Flex is a tool for generating scanners. A scanner, sometimes
+called a tokenizer, is a program which recognizes lexical patterns in
+text. The flex program reads user-specified input files, or its standard
+input if no file names are given, for a description of a scanner to
+generate. The description is in the form of pairs of regular expressions
+and C code, called rules. Flex generates a C source file named,
+\"lex.yy.c\", which defines the function yylex(). The file \"lex.yy.c\"
+can be compiled and linked to produce an executable. When the executable
+is run, it analyzes its input for occurrences of text matching the
+regular expressions for each rule. Whenever it finds a match, it
+executes the corresponding C code.")
+    (license "BSD")))

distro/packages/patches/flex-bison-tests.patch

@@ -0,0 +1,24 @@
+The `test-bison-yyl{loc,val}' tests fail with "conflicting types for
+'testparse'" because `YYPARSE_PARAM' is undefined; work around that.
+
+--- flex-2.5.37/tests/test-bison-yylloc/main.c	2012-11-22 18:17:01.000000000 +0100
++++ flex-2.5.37/tests/test-bison-yylloc/main.c	2012-11-22 18:17:07.000000000 +0100
+@@ -21,6 +21,7 @@
+  * PURPOSE.
+  */
+ 
++#define YYPARSE_PARAM scanner
+ #include "parser.h"
+ #include "scanner.h"
+ 
+
+--- flex-2.5.37/tests/test-bison-yylval/main.c	2012-11-22 18:17:42.000000000 +0100
++++ flex-2.5.37/tests/test-bison-yylval/main.c	2012-11-22 18:17:49.000000000 +0100
+@@ -21,6 +21,7 @@
+  * PURPOSE.
+  */
+ 
++#define YYPARSE_PARAM scanner
+ #include "parser.h"
+ #include "scanner.h"
+