Restore apc_arginfo.h header

This is a reexport of php_apc_legacy_arginfo.h for use by apcu_bc.
It intentionally fails the build on PHP 8, as apcu_bc will not be
supported on PHP 8.

apc_arginfo.h

@@ -0,0 +1,5 @@
+#if PHP_VERSION_ID < 80000
+# include "php_apc_legacy_arginfo.h"
+#else
+# error Not supported on PHP >= 8.0
+#endif

config.m4

@@ -243,7 +243,7 @@ if test "$PHP_APCU" != "no"; then
   PHP_SUBST(APCU_SHARED_LIBADD)
   PHP_SUBST(APCU_CFLAGS)
   PHP_SUBST(PHP_LDFLAGS)
-  PHP_INSTALL_HEADERS(ext/apcu, [php_apc.h apc.h apc_api.h apc_cache.h apc_cache_api.h apc_globals.h apc_iterator.h apc_lock.h apc_mutex.h apc_lock_api.h apc_sma.h apc_sma_api.h apc_serializer.h apc_stack.h])
+  PHP_INSTALL_HEADERS(ext/apcu, [php_apc.h apc.h apc_api.h apc_cache.h apc_cache_api.h apc_globals.h apc_iterator.h apc_lock.h apc_mutex.h apc_lock_api.h apc_sma.h apc_sma_api.h apc_serializer.h apc_stack.h apc_arginfo.h php_apc_legacy_arginfo.h])
   AC_DEFINE(HAVE_APCU, 1, [ ])
 fi
 

config.w32

@@ -24,7 +24,7 @@ if(PHP_APCU != 'no')
 	AC_DEFINE('APC_SRWLOCK_KERNEL', 1);
 	AC_DEFINE('HAVE_APCU', 1);
 	ADD_FLAG('CFLAGS_APCU', '/D WIN32_ONLY_COMPILER=1 /DAPC_SRWLOCK_KERNEL=1');
-	PHP_INSTALL_HEADERS("ext/apcu", "php_apc.h apc.h apc_api.h apc_cache.h apc_cache_api.h apc_globals.h apc_iterator.h apc_lock.h apc_mutex.h apc_lock_api.h apc_sma.h apc_sma_api.h apc_serializer.h apc_stack.h apc_windows_srwlock_kernel.h");
+	PHP_INSTALL_HEADERS("ext/apcu", "php_apc.h apc.h apc_api.h apc_cache.h apc_cache_api.h apc_globals.h apc_iterator.h apc_lock.h apc_mutex.h apc_lock_api.h apc_sma.h apc_sma_api.h apc_serializer.h apc_stack.h apc_windows_srwlock_kernel.h apc_arginfo.h php_apc_legacy_arginfo.h");
 
 	EXTENSION('apcu', apc_sources, PHP_APCU_SHARED, "/DZEND_ENABLE_STATIC_TSRMLS_CACHE=1");
 }