[Ada] Do not include crt_externs.h on iOS

2018-11-14  Jerome Lambourg  <lambourg@adacore.com>

gcc/ada/

	* env.c: Do not include crt_externs.h on iOS, as it does not
	exist there. This is also true for the iPhone Simulator SDK.

From-SVN: r266118

gcc/ada/ChangeLog

+2018-11-14  Jerome Lambourg  <lambourg@adacore.com>
+
+	* env.c: Do not include crt_externs.h on iOS, as it does not
+	exist there. This is also true for the iPhone Simulator SDK.
+
 2018-11-14  Ed Schonberg  <schonberg@adacore.com>
 
 	* exp_ch7.adb (Check_Unnesting_In_Declarations): New procedure

gcc/ada/env.c

@@ -50,9 +50,12 @@
 #include <stdlib.h>
 #endif
 
-#if defined (__APPLE__) && !(defined (__arm__) || defined (__arm64__))
+#if defined (__APPLE__) \
+   && !(defined (__arm__) \
+        || defined (__arm64__) \
+        || defined (__IOS_SIMULATOR__))
 /* On Darwin, _NSGetEnviron must be used for shared libraries; but it is not
-   available on iOS.  */
+   available on iOS (on device or on simulator).  */
 #include <crt_externs.h>
 #endif
 
@@ -211,7 +214,10 @@ __gnat_environ (void)
 #elif defined (__sun__)
   extern char **_environ;
   return _environ;
-#elif defined (__APPLE__) && !(defined (__arm__) || defined (__arm64__))
+#elif defined (__APPLE__) \
+     && !(defined (__arm__) \
+          || defined (__arm64__)                \
+          || defined (__IOS_SIMULATOR__))
   return *_NSGetEnviron ();
 #elif ! (defined (__vxworks))
   extern char **environ;