darwin: Add __xxx_OS_VERSION_MIN constants for Darwin platforms

mak/COPY

@@ -100,6 +100,7 @@ COPY=\
 	$(IMPDIR)\core\sys\bionic\string.d \
 	$(IMPDIR)\core\sys\bionic\unistd.d \
 	\
+	$(IMPDIR)\core\sys\darwin\config.d \
 	$(IMPDIR)\core\sys\darwin\crt_externs.d \
 	$(IMPDIR)\core\sys\darwin\dlfcn.d \
 	$(IMPDIR)\core\sys\darwin\err.d \

src/core/sys/darwin/config.d

@@ -0,0 +1,96 @@
+/**
+ * D header file for Darwin.
+ *
+ * Copyright: Copyright (c) 2020 D Language Foundation
+ * Authors: Iain Buclaw
+ */
+module core.sys.darwin.config;
+
+version (OSX)
+    version = Darwin;
+else version (iOS)
+    version = Darwin;
+else version (TVOS)
+    version = Darwin;
+else version (WatchOS)
+    version = Darwin;
+
+version (Darwin):
+
+public import core.sys.posix.config;
+
+// In the OSX Availability headers, a developer can specify a MIN_REQUIRED and
+// a MAX_ALLOWED version number to control the OS functionality.  Here, there
+// is only a lower bound version number `__MAC_OS_X_VERSION_MIN` exposed, these
+// are gated by predefined version conditions added in the compiler, and map to
+// the setting of the following compiler options.
+//  -mmacosx-version-min=   (on OSX)
+//  -miphoneos-version-min= (on iOS)
+//  -mtvos-version-min=     (on TVOS)
+//  -mwatchos-version-min=  (on WatchOS)
+
+enum __MAC_10_5  = 1050;
+enum __MAC_10_6  = 1060;
+enum __MAC_10_7  = 1070;
+enum __MAC_10_8  = 1080;
+enum __MAC_10_9  = 1090;
+enum __MAC_10_10 = 101000;
+enum __MAC_10_11 = 101100;
+enum __MAC_10_12 = 101200;
+
+     version (OSX_10_5)  enum __MAC_OS_X_VERSION_MIN = __MAC_10_5;
+else version (OSX_10_6)  enum __MAC_OS_X_VERSION_MIN = __MAC_10_6;
+else version (OSX_10_7)  enum __MAC_OS_X_VERSION_MIN = __MAC_10_7;
+else version (OSX_10_8)  enum __MAC_OS_X_VERSION_MIN = __MAC_10_8;
+else version (OSX_10_9)  enum __MAC_OS_X_VERSION_MIN = __MAC_10_9;
+else version (OSX_10_10) enum __MAC_OS_X_VERSION_MIN = __MAC_10_10;
+else version (OSX_10_11) enum __MAC_OS_X_VERSION_MIN = __MAC_10_11;
+else version (OSX_10_12) enum __MAC_OS_X_VERSION_MIN = __MAC_10_12;
+else                     enum __MAC_OS_X_VERSION_MIN = __MAC_10_9;
+
+enum __IPHONE_9_0  = 90000;
+enum __IPHONE_9_1  = 90100;
+enum __IPHONE_9_2  = 90200;
+enum __IPHONE_9_3  = 90300;
+enum __IPHONE_10_0 = 100000;
+enum __IPHONE_10_1 = 100100;
+enum __IPHONE_10_2 = 100200;
+enum __IPHONE_10_3 = 100300;
+
+     version (iOS_9_0)  enum __IPHONE_OS_VERSION_MIN = __IPHONE_9_0;
+else version (iOS_9_1)  enum __IPHONE_OS_VERSION_MIN = __IPHONE_9_1;
+else version (iOS_9_2)  enum __IPHONE_OS_VERSION_MIN = __IPHONE_9_2;
+else version (iOS_9_3)  enum __IPHONE_OS_VERSION_MIN = __IPHONE_9_3;
+else version (iOS_10_0) enum __IPHONE_OS_VERSION_MIN = __IPHONE_10_0;
+else version (iOS_10_1) enum __IPHONE_OS_VERSION_MIN = __IPHONE_10_1;
+else version (iOS_10_2) enum __IPHONE_OS_VERSION_MIN = __IPHONE_10_2;
+else version (iOS_10_3) enum __IPHONE_OS_VERSION_MIN = __IPHONE_10_3;
+else                    enum __IPHONE_OS_VERSION_MIN = __IPHONE_9_0;
+
+enum __TVOS_9_0  = 90000;
+enum __TVOS_9_1  = 90100;
+enum __TVOS_9_2  = 90200;
+enum __TVOS_10_0 = 100000;
+enum __TVOS_10_1 = 100100;
+enum __TVOS_10_2 = 100200;
+
+version (TVOS_9_0)  enum __TV_OS_VERSION_MIN = __TVOS_9_0;
+version (TVOS_9_1)  enum __TV_OS_VERSION_MIN = __TVOS_9_1;
+version (TVOS_9_2)  enum __TV_OS_VERSION_MIN = __TVOS_9_2;
+version (TVOS_10_0) enum __TV_OS_VERSION_MIN = __TVOS_10_0;
+version (TVOS_10_1) enum __TV_OS_VERSION_MIN = __TVOS_10_1;
+version (TVOS_10_2) enum __TV_OS_VERSION_MIN = __TVOS_10_2;
+else                enum __TV_OS_VERSION_MIN = __TVOS_10_0;
+
+enum __WATCHOS_1_0 = 10000;
+enum __WATCHOS_2_0 = 20000;
+enum __WATCHOS_3_0 = 30000;
+enum __WATCHOS_3_1 = 30100;
+enum __WATCHOS_3_2 = 30200;
+
+version (WatchOS_1_0) enum __WATCH_OS_VERSION_MIN = __WATCHOS_1_0;
+version (WatchOS_2_0) enum __WATCH_OS_VERSION_MIN = __WATCHOS_2_0;
+version (WatchOS_3_0) enum __WATCH_OS_VERSION_MIN = __WATCHOS_3_0;
+version (WatchOS_3_1) enum __WATCH_OS_VERSION_MIN = __WATCHOS_3_1;
+version (WatchOS_3_2) enum __WATCH_OS_VERSION_MIN = __WATCHOS_3_2;
+else                  enum __WATCH_OS_VERSION_MIN = __WATCHOS_3_0;