Remove HAVE_JSON symbol (#13277)

The json extension is always available as of php 8.0. HAVE_JSON was also
never defined for Windows builds.

Author: petk

UPGRADING.INTERNALS

@@ -53,6 +53,8 @@ PHP 8.4 INTERNALS UPGRADE NOTES
    - HAVE_ODBC2 symbol has been removed in ext/odbc.
    - Removed linking with obsolete dnet_stub library in ext/pdo_dblib.
    - Removed checking and linking with obsolete libbind for some functions.
+   - Symbol HAVE_JSON has been removed (ext/json is always available since PHP
+     8.0).
 
  c. Windows build system changes
    - Added Bison flag '-Wall' when generating lexer files as done in *nix build

ext/json/config.m4

@@ -1,6 +1,3 @@
-dnl HAVE_JSON is always 1 as of php 8.0 and the constant will be removed in the future.
-dnl Note that HAVE_JSON was never defined for Windows builds (see config.w32)
-AC_DEFINE([HAVE_JSON],1 ,[whether to enable JavaScript Object Serialization support])
 PHP_NEW_EXTENSION(json,
 	  json.c \
 	  json_encoder.c \