ocaml 4.10/4.11: fix build w/glibc-2.34

Failing Hydra build: https://hydra.nixos.org/build/155189331
Applied a smaller patch from Fedora's fork[1] as it also applies on
older versions.

That said, these versions seem unmaintained anyways, so we should
probably drop them entirely.

[1] https://pagure.io/fedora-ocaml/c/dfb5e954a04f59b0456cc4c0ddf3acaf22e0ff07?branch=fedora-35-4.12.0

pkgs/development/compilers/ocaml/4.10.nix

@@ -3,4 +3,7 @@ import ./generic.nix {
   minor_version = "10";
   patch_version = "2";
   sha256 = "sha256-locUYQeCgtXbAiB32JveJchfteN2YStE+MN9ToTwAOM=";
+  patches = [
+    ./glibc-2.34-for-ocaml-4.10-and-11.patch
+  ];
 }

pkgs/development/compilers/ocaml/4.11.nix

@@ -3,4 +3,7 @@ import ./generic.nix {
   minor_version = "11";
   patch_version = "2";
   sha256 = "1m3wrgkkv3f77wvcymjm0i2srxzmx62y6jln3i0a2px07ng08l9z";
+  patches = [
+    ./glibc-2.34-for-ocaml-4.10-and-11.patch
+  ];
 }

pkgs/development/compilers/ocaml/generic.nix

@@ -35,6 +35,8 @@ let
   x11env = buildEnv { name = "x11env"; paths = [libX11 xorgproto]; };
   x11lib = x11env + "/lib";
   x11inc = x11env + "/include";
+
+  fetchpatch' = x: if builtins.isAttrs x then fetchpatch x else x;
 in
 
 stdenv.mkDerivation (args // {
@@ -44,7 +46,7 @@ stdenv.mkDerivation (args // {
 
   inherit src;
 
-  patches = map fetchpatch patches;
+  patches = map fetchpatch' patches;
 
   strictDeps = true;
 

pkgs/development/compilers/ocaml/glibc-2.34-for-ocaml-4.10-and-11.patch

@@ -0,0 +1,37 @@
+From dfb5e954a04f59b0456cc4c0ddf3acaf22e0ff07 Mon Sep 17 00:00:00 2001
+From: Richard W.M. Jones <rjones@redhat.com>
+Date: Feb 28 2021 20:45:47 +0000
+Subject: Workaround for glibc non-constant SIGSTKSZ
+
+
+https://github.com/ocaml/ocaml/issues/10250
+
+Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
+
+---
+
+diff --git a/runtime/signals_nat.c b/runtime/signals_nat.c
+index 8b64ab4..7f0a975 100644
+--- a/runtime/signals_nat.c
++++ b/runtime/signals_nat.c
+@@ -181,7 +181,19 @@ DECLARE_SIGNAL_HANDLER(trap_handler)
+ #error "CONTEXT_SP is required if HAS_STACK_OVERFLOW_DETECTION is defined"
+ #endif
+ 
++#ifndef __GLIBC__
+ static char sig_alt_stack[SIGSTKSZ];
++#else
++/* glibc 2.34 has non-constant SIGSTKSZ */
++static char *sig_alt_stack;
++
++static void allocate_sig_alt_stack(void) __attribute__((constructor));
++static void
++allocate_sig_alt_stack(void)
++{
++  sig_alt_stack = malloc(SIGSTKSZ);
++}
++#endif
+ 
+ /* Code compiled with ocamlopt never accesses more than
+    EXTRA_STACK bytes below the stack pointer. */
+