Libc: Define target instead of including

Including `TargetConditionals.h` had knock-on effects, breaking the zlib
build because `TARGET_OS_MAC` gets defined, for instance.

Defining `TARGET_OS_EMBEDDED` to be `0` if it's not defined is simpler
and maintains the default behavior so it shouldn't break any dependents.

pkgs/os-specific/darwin/apple-source-releases/Libc/0001-Define-TARGET_OS_EMBEDDED-in-stdlib-if-not-defined.patch

@@ -0,0 +1,32 @@
+From c0ab867bb7888401957539b0348902028a2be6e0 Mon Sep 17 00:00:00 2001
+From: toonn <toonn@toonn.io>
+Date: Tue, 27 Jul 2021 15:12:14 +0200
+Subject: [PATCH] Define TARGET_OS_EMBEDDED in stdlib if not defined
+
+Originally attempted including `TargetConditionals.h` but this had
+knock-on effects, for example, breaking the zlib build because of
+`TARGET_OS_MAC` getting defined.
+
+This should be the lowest impact solution and corresponds to the default
+behavior IIUC.
+---
+ include/stdlib.h | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/include/stdlib.h b/include/stdlib.h
+index c04d3a7..0b454ba 100644
+--- a/include/stdlib.h
++++ b/include/stdlib.h
+@@ -183,6 +183,9 @@ unsigned long long
+ #ifndef LIBC_ALIAS_SYSTEM
+ //End-Libc
+ 
++#ifndef TARGET_OS_EMBEDDED
++#  define TARGET_OS_EMBEDDED 0
++#endif
+ #if TARGET_OS_EMBEDDED
+ #define __swift_unavailable_on(osx_msg, ios_msg) __swift_unavailable(ios_msg)
+ #else
+-- 
+2.17.2 (Apple Git-113)
+

pkgs/os-specific/darwin/apple-source-releases/Libc/0001-Include-Targetconditionals-in-stdlib.patch

@@ -1,24 +0,0 @@
-From 6e573a85b46dcfae323a99aa561c0dcc016a7791 Mon Sep 17 00:00:00 2001
-From: toonn <toonn@toonn.io>
-Date: Mon, 26 Jul 2021 16:19:44 +0200
-Subject: [PATCH] Include Targetconditionals in stdlib
-
----
- include/stdlib.h | 1 +
- 1 file changed, 1 insertion(+)
-
-diff --git a/include/stdlib.h b/include/stdlib.h
-index c04d3a7..94a9812 100644
---- a/include/stdlib.h
-+++ b/include/stdlib.h
-@@ -59,6 +59,7 @@
- #define _STDLIB_H_
- 
- #include <Availability.h>
-+#include <TargetConditionals.h>
- 
- #include <_types.h>
- #if !defined(_ANSI_SOURCE)
--- 
-2.17.2 (Apple Git-113)
-

pkgs/os-specific/darwin/apple-source-releases/Libc/default.nix

@@ -3,7 +3,7 @@
 appleDerivation' stdenvNoCC {
   nativeBuildInputs = [ ed unifdef ];
 
-  patches = [ ./0001-Include-Targetconditionals-in-stdlib.patch ];
+  patches = [ ./0001-Define-TARGET_OS_EMBEDDED-in-stdlib-if-not-defined.patch ];
 
   # TODO: asl.h actually comes from syslog project now
   installPhase = ''