Revert "gnum4: 1.4.19 -> 1.4.20" (#417441)

pkgs/by-name/gn/gnum4/loong-fix-build.patch

@@ -0,0 +1,30 @@
+[xen0n: this is https://github.com/sunhaiyong1978/CLFS-for-LoongArch/blob/1.0/patches/stack-direction-add-loongarch.patch with line number tweak, and change to generated file added as well.]
+From: Sun Haiyong <youbest@sina.com>
+Date: Tue, 31 Aug 2021 11:11:52 +0800
+Subject: [PATCH] stack-direction: Add support for loongarch CPU
+
+* m4/stack-direction.m4 (SV_STACK_DIRECTION): When the CPU is loongarch,
+set "sv_cv_stack_direction" to "-1" .
+--- a/m4/stack-direction.m4
++++ b/m4/stack-direction.m4
+@@ -31,6 +31,7 @@ AC_DEFUN([SV_STACK_DIRECTION],
+       i?86 | x86_64 | \
+       i860 | \
+       ia64 | \
++      loongarch* | \
+       m32r | \
+       m68* | \
+       m88k | \
+--- a/configure
++++ b/configure
+@@ -46399,6 +46399,7 @@ else $as_nop
+       i?86 | x86_64 | \
+       i860 | \
+       ia64 | \
++      loongarch* | \
+       m32r | \
+       m68* | \
+       m88k | \
+-- 
+2.17.2
+

pkgs/by-name/gn/gnum4/package.nix

@@ -11,13 +11,15 @@
 
 stdenv.mkDerivation rec {
   pname = "gnum4";
-  version = "1.4.20";
+  version = "1.4.19";
 
   src = fetchurl {
     url = "mirror://gnu/m4/m4-${version}.tar.bz2";
-    hash = "sha256-rGmJ7l0q7YFzl4BjDMLOCX4qZUb+uWpKVNs31GoUUuQ=";
+    sha256 = "sha256-swapHA/ZO8QoDPwumMt6s5gf91oYe+oyk4EfRSyJqMg=";
   };
 
+  # https://gitweb.gentoo.org/repo/gentoo.git/tree/sys-devel/m4/m4-1.4.19-r1.ebuild
+  patches = lib.optional stdenv.hostPlatform.isLoongArch64 ./loong-fix-build.patch;
   # this could be accomplished by updateAutotoolsGnuConfigScriptsHook, but that causes infinite recursion
   # necessary for FreeBSD code path in configure
   postPatch =