[skip ci] PHP 8.4 changelog: fix typo in new constant

Ref: PR 15479 / d713e36

Author: jrfnl

UPGRADING

@@ -1063,7 +1063,7 @@ PHP 8.4 UPGRADE NOTES
   . IP_PORTRANGE_LOW (FreeBSD/NetBSD/OpenBSD only).
   . SOCK_NONBLOCK.
   . SOCK_CLOEXEC.
-  . SOCK_BINDTOIFINDEX.
+  . SO_BINDTOIFINDEX.
 
 - Sodium:
   . SODIUM_CRYPTO_AEAD_AEGIS128L_KEYBYTES