Remove obsolete checks for random-related functionality from ext/standard/config.m4 (#9482)

The users of these checks have been moved to ext/random. ext/standard does not
reference the resulting defines.

Author: TimWolla

ext/standard/config.m4

@@ -398,22 +398,6 @@ if test "$ac_cv_strptime_decl_fails" = "yes"; then
   AC_DEFINE([HAVE_STRPTIME_DECL_FAILS], 1, [whether strptime() declaration fails])
 fi
 
-dnl
-dnl Check for arc4random on BSD systems
-dnl
-AC_CHECK_DECLS([arc4random_buf])
-
-dnl
-dnl Check for CCRandomGenerateBytes
-dnl header absent in previous macOs releases
-dnl
-AC_CHECK_HEADERS([CommonCrypto/CommonRandom.h], [], [],
-[
-	#include <sys/types.h>
-	#include <Availability.h>
-	#include <CommonCrypto/CommonCryptoError.h>
-])
-
 dnl
 dnl Check for argon2
 dnl