darwin.CF: Include missing TARGET_OS_* defines

This patch is static and may not be appropriate if the compilation
target is iOS.

pkgs/os-specific/darwin/swift-corelibs/0001-Add-missing-TARGET_OS_-defines.patch

···
+From 549160574ee44656d50997b27ef83736e0848201 Mon Sep 17 00:00:00 2001
+From: toonn <[e-mail]>
+Date: Mon, 26 Apr 2021 20:51:05 +0200
+Subject: [PATCH] Add missing TARGET_OS_* defines
+
+---
+ .../Base.subproj/SwiftRuntime/TargetConditionals.h         | 7 +++++++
+ 1 file changed, 7 insertions(+)
+
+diff --git a/CoreFoundation/Base.subproj/SwiftRuntime/TargetConditionals.h b/CoreFoundation/Base.subproj/SwiftRuntime/TargetConditionals.h
+index 6d42b873..abf746c9 100644
+--- a/CoreFoundation/Base.subproj/SwiftRuntime/TargetConditionals.h
++++ b/CoreFoundation/Base.subproj/SwiftRuntime/TargetConditionals.h
+@@ -118,6 +118,13 @@
+ 
+ #define TARGET_OS_WIN32        TARGET_OS_WINDOWS
+ #define TARGET_OS_MAC          TARGET_OS_DARWIN
++#define TARGET_OS_OSX          TARGET_OS_DARWIN
++
++#define TARGET_OS_IPHONE       0
++#define TARGET_OS_WATCH        0
++#define TARGET_OS_TV           0
++#define TARGET_OS_EMBEDDED     0
++
+ 
+ #if __x86_64__
+ #define TARGET_CPU_PPC          0
+-- 
+2.17.2 (Apple Git-113)
+

pkgs/os-specific/darwin/swift-corelibs/corefoundation.nix

···
   nativeBuildInputs = [ ninja python3 ];
   buildInputs = [ curl libxml2 objc4 ICU ];
 
+  patches = [ ./0001-Add-missing-TARGET_OS_-defines.patch ];
+
   postPatch = ''
     cd CoreFoundation
 
···
   # please remove this when updating the default llvm versions to 8 or
   # later.
   buildPhase = lib.optionalString true ''
-    for i in {1..512}; do
+    for i in {1..1}; do
         if ninja -j $NIX_BUILD_CORES; then
             break
         fi