Darwin platform allows to build on releases before Yosemite/ios 8.

backport #16409

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16418)

include/crypto/rand.h

@@ -22,6 +22,16 @@
 # include <openssl/rand.h>
 # include "crypto/rand_pool.h"
 
+# if defined(__APPLE__) && !defined(OPENSSL_NO_APPLE_CRYPTO_RANDOM)
+#  include <Availability.h>
+#  if (defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED >= 101000) || \
+     (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED >= 80000)
+#   define OPENSSL_APPLE_CRYPTO_RANDOM 1
+#   include <CommonCrypto/CommonCryptoError.h>
+#   include <CommonCrypto/CommonRandom.h>
+#  endif
+# endif
+
 /*
  * Defines related to seed sources
  */

providers/implementations/rands/seeding/rand_unix.c

@@ -40,10 +40,6 @@
 # include <sys/param.h>
 # include <sys/random.h>
 #endif
-#if defined(__APPLE__)
-# include <CommonCrypto/CommonCryptoError.h>
-# include <CommonCrypto/CommonRandom.h>
-#endif
 
 #if (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS)) \
      || defined(__DJGPP__)
@@ -370,7 +366,7 @@ static ssize_t syscall_random(void *buf, size_t buflen)
         if (errno != ENOSYS)
             return -1;
     }
-#    elif defined(__APPLE__)
+#    elif defined(OPENSSL_APPLE_CRYPTO_RANDOM)
 
     if (CCRandomGenerateBytes(buf, buflen) == kCCSuccess)
 	    return (ssize_t)buflen;