Revert "syslinux: 2015-11-09 -> 2019-02-07"

This reverts commit 0b49d5dd68 #55500.
I'm sorry, I'm unable to fix the build quickly in other way than
atop the older version.  Certainly feel free to improve the approach.

pkgs/os-specific/linux/syslinux/default.nix

@@ -1,19 +1,31 @@
-{ stdenv, fetchFromRepoOrCz, fetchpatch, nasm, perl, python, libuuid, mtools, makeWrapper }:
+{ stdenv, fetchFromGitHub, fetchurl, nasm, perl, python, libuuid, mtools, makeWrapper }:
 
 stdenv.mkDerivation rec {
-  # This is syslinux-6.04-pre3^1; syslinux-6.04-pre3 fails to run.
-  # Same issue here https://www.syslinux.org/archives/2019-February/026330.html
-  name = "syslinux-2019-02-07";
+  name = "syslinux-2015-11-09";
 
-  src = fetchFromRepoOrCz {
+  src = fetchFromGitHub {
+    owner = "geneC";
     repo = "syslinux";
-    rev = "b40487005223a78c3bb4c300ef6c436b3f6ec1f7";
-    sha256 = "1qrxl1114sr2i2791z9rf8v53g200aq30f08808d7i8qnmgvxl2w";
+    rev = "0cc9a99e560a2f52bcf052fd85b1efae35ee812f";
+    sha256 = "0wk3r5ki4lc334f9jpml07wpl8d0bnxi9h1l4h4fyf9a0d7n4kmw";
   };
 
+  patches = [
+    ./perl-deps.patch
+    (fetchurl {
+      # ldlinux.elf: Not enough room for program headers, try linking with -N
+      name = "not-enough-room.patch";
+      url = "https://anonscm.debian.org/cgit/collab-maint/syslinux.git/plain/"
+          + "debian/patches/0014_fix_ftbfs_no_dynamic_linker.patch?id=a556ad7";
+      sha256 = "0ijqjsjmnphmvsx0z6ppnajsfv6xh6crshy44i2a5klxw4nlvrsw";
+    })
+  ];
+
   postPatch = ''
     substituteInPlace Makefile --replace /bin/pwd $(type -P pwd)
+    substituteInPlace gpxe/src/Makefile.housekeeping --replace /bin/echo $(type -P echo)
     substituteInPlace utils/ppmtolss16 --replace /usr/bin/perl $(type -P perl)
+    substituteInPlace gpxe/src/Makefile --replace /usr/bin/perl $(type -P perl)
 
     # fix tests
     substituteInPlace tests/unittest/include/unittest/unittest.h \