Remove ext/random backwards-compatibility headers (#13108)

When ext/random was initially added in PHP 8.2, these headers started
“forwarding” to the new ext/random/php_random.h to reduce the impact on
existing extensions.

As master already contains some breaking changes of the internal API of
ext/random and as the last PHP version without ext/random will be EOL once
master is released, it appears appropriate to drop these headers now.

Author: TimWolla

UPGRADING.INTERNALS

@@ -30,6 +30,10 @@ PHP 8.4 INTERNALS UPGRADE NOTES
   int(*)(zend_object_iterator *) to zend_result(*)(zend_object_iterator *) to
   be more in line with what callbacks are returning.
 
+* The backwards compatibility headers ext/standard/{php_lcg.h,php_mt_rand.h,
+  php_rand.h,php_random.h} have been removed. Include ext/random/php_random.h
+  directly.
+
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