gnu: screen: Build fix for the Hurd.

* gnu/packages/patches/screen-hurd-path-max.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/screen.scm (screen): Use it.

gnu/local.mk

@@ -1424,6 +1424,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/scheme48-tests.patch			\
   %D%/packages/patches/scotch-build-parallelism.patch		\
   %D%/packages/patches/scotch-integer-declarations.patch	\
+  %D%/packages/patches/screen-hurd-path-max.patch		\
   %D%/packages/patches/sdl-libx11-1.6.patch			\
   %D%/packages/patches/sdl2-mesa-compat.patch			\
   %D%/packages/patches/seahorse-gkr-use-0-on-empty-flags.patch	\

gnu/packages/patches/screen-hurd-path-max.patch

@@ -0,0 +1,42 @@
+Workaround for PATH_MAX usage on the Hurd.
+
+Taken from https://salsa.debian.org/debian/screen/-/blob/master/debian/patches/61-default-PATH_MAX-if-undefined-for-hurd.patch
+
+Description: Set PATH_MAX to 4096 if undefined
+ Fixes FTBFS since 4.4.0 on GNU/Hurd. Updated to add one more occurrence for 4.5.0.
+Author: Axel Beckert <abe@debian.org>
+Bug: https://savannah.gnu.org/bugs/?50089
+Last-Updated: 2017-01-18
+
+--- a/tty.sh
++++ b/tty.sh
+@@ -1478,6 +1478,13 @@
+   return 0;
+ }
+ 
++/*
++ * Define PATH_MAX to 4096 if it's not defined, like on GNU/Hurd
++ */
++
++#ifndef PATH_MAX
++#define PATH_MAX 4096
++#endif
+ 
+ int CheckTtyname (char *tty)
+ {
+--- a/screen.h
++++ b/screen.h
+@@ -109,6 +109,13 @@
+ # define DEFAULT_BUFFERFILE	"/tmp/screen-exchange"
+ #endif
+ 
++/*
++ * Define PATH_MAX to 4096 if it's not defined, like on GNU/Hurd
++ */
++
++#ifndef PATH_MAX
++#define PATH_MAX 4096
++#endif
+ 
+ #if defined(hpux) && !(defined(VSUSP) && defined(VDSUSP) && defined(VWERASE) && defined(VLNEXT))
+ # define HPUX_LTCHARS_HACK

gnu/packages/screen.scm

@@ -29,6 +29,7 @@
   #:use-module (guix git-download)
   #:use-module (guix build-system gnu)
   #:use-module (gnu packages)
+  #:use-module (gnu packages hurd)
   #:use-module (gnu packages ncurses)
   #:use-module (gnu packages perl)
   #:use-module (gnu packages python)
@@ -43,6 +44,7 @@
              (method url-fetch)
              (uri (string-append "mirror://gnu/screen/screen-"
                                  version ".tar.gz"))
+             (patches (search-patches "screen-hurd-path-max.patch"))
              (sha256
               (base32 "18ascpjzsy70h6hk7wpg8zmzjwgdyrdr7c6z4pg5z4l9hhyv24bf"))))
     (build-system gnu-build-system)