distro: Add GNU M4.

* distro/base.scm (m4): New variable.

* distro/m4-readlink-EINVAL.patch, distro/m4-s_isdir.patch: New files.
* Makefile.am (nobase_dist_guilemodule_DATA): Add them.

Makefile.am

@@ -37,7 +37,9 @@ GOBJECTS = $(MODULES:%.scm=%.go)
 
 nobase_dist_guilemodule_DATA =			\
   $(MODULES)					\
-  distro/guile-1.8-cpp-4.5.patch
+  distro/guile-1.8-cpp-4.5.patch		\
+  distro/m4-readlink-EINVAL.patch		\
+  distro/m4-s_isdir.patch
 
 nobase_nodist_guilemodule_DATA = $(GOBJECTS)
 

distro/base.scm

@@ -108,6 +108,54 @@ code.")
    (home-page "http://www.gnu.org/software/hello/")
    (license "GPLv3+")))
 
+(define-public m4
+  (package
+   (name "m4")
+   (version "1.4.16")
+   (source (origin
+            (method http-fetch)
+            (uri (string-append "http://ftp.gnu.org/gnu/m4/m4-"
+                                version ".tar.bz2"))
+            (sha256
+             (base32
+              "035r7ma272j2cwni2961jp22k6bn3n9xwn3b3qbcn2yrvlghql22"))))
+   (build-system gnu-build-system)
+   (arguments (case-lambda
+                ((system)
+                 ;; XXX: Disable tests on those platforms with know issues.
+                 `(#:tests? ,(not (member system
+                                          '("x86_64-darwin"
+                                            "i686-cygwin"
+                                            "i686-sunos")))
+                   #:patches (list (assoc-ref %build-inputs "patch/s_isdir")
+                                   (assoc-ref %build-inputs
+                                              "patch/readlink-EINVAL"))))
+                ((system cross-system)
+                 `(#:patches (list (assoc-ref %build-inputs "patch/s_isdir")
+                                   (assoc-ref %build-inputs
+                                              "patch/readlink-EINVAL"))))))
+   (inputs `(("patch/s_isdir"
+              ,(search-path %load-path "distro/m4-s_isdir.patch"))
+             ("patch/readlink-EINVAL"
+              ,(search-path %load-path "distro/m4-readlink-EINVAL.patch"))))
+   (description "GNU M4, a macro processor")
+   (long-description
+    "GNU M4 is an implementation of the traditional Unix macro processor.  It
+is mostly SVR4 compatible although it has some extensions (for example,
+handling more than 9 positional parameters to macros).  GNU M4 also has
+built-in functions for including files, running shell commands, doing
+arithmetic, etc.
+
+GNU M4 is a macro processor in the sense that it copies its input to the
+output expanding macros as it goes.  Macros are either builtin or
+user-defined and can take any number of arguments.  Besides just doing macro
+expansion, m4 has builtin functions for including named files, running UNIX
+commands, doing integer arithmetic, manipulating text in various ways,
+recursion etc...  m4 can be used either as a front-end to a compiler or as a
+macro processor in its own right.")
+   (license "GPLv3+")
+   (home-page "http://www.gnu.org/software/m4/")))
+
 (define-public guile-1.8
   (package
    (name "guile")

distro/m4-readlink-EINVAL.patch

@@ -0,0 +1,18 @@
+Newer Linux kernels would return EINVAL instead of ENOENT.
+The patch below, taken from Gnulib, allows the test to pass when
+these Linux versions are in use:
+https://lists.gnu.org/archive/html/bug-gnulib/2011-03/msg00308.html .
+
+diff --git a/tests/test-readlink.h b/tests/test-readlink.h
+index 08d5662..7247fc4 100644
+--- a/tests/test-readlink.h
++++ b/tests/test-readlink.h
+@@ -38,7 +38,7 @@ test_readlink (ssize_t (*func) (char const *, char *, size_t), bool print)
+   ASSERT (errno == ENOENT);
+   errno = 0;
+   ASSERT (func ("", buf, sizeof buf) == -1);
+-  ASSERT (errno == ENOENT);
++  ASSERT (errno == ENOENT || errno == EINVAL);
+   errno = 0;
+   ASSERT (func (".", buf, sizeof buf) == -1);
+   ASSERT (errno == EINVAL);

distro/m4-s_isdir.patch

@@ -0,0 +1,14 @@
+Fails to build with glibc 2.12.1 without this patch.
+
+http://lists.gnu.org/archive/html/bug-m4/2010-05/msg00002.html
+
+--- a/src/path.c
++++ b/src/path.c
+@@ -22,6 +22,7 @@
+ /* Handling of path search of included files via the builtins "include"
+    and "sinclude".  */
+ 
+ #include "m4.h"
++#include "sys/stat.h"
+ 
+ struct includes