Implemented the RFC `Support Class Constant Visibility`.

Squashed commit of the following:

commit f11ca0e7a57793fa0e3e7f6d451720e6c42bb0b9
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Tue Dec 8 12:38:42 2015 +0300

    Fixed test expectation

commit 211f873f542504d0a0f72b6b5cb23908a1c99a2d
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Tue Dec 8 12:28:38 2015 +0300

    Embed zend_class_constant.flags into zend_class_constants.value.u2.access_flags

commit 51deab84b2cdbf9cdb1a838cf33b2ee45c61748b
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Mon Dec 7 11:18:55 2015 +0300

    Fixed issues found by Nikita

commit 544dbd5b47e40d38a8ccb96bc5583e9cb7fdd723
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Sat Dec 5 02:41:05 2015 +0300

    Refactored immplementation of https://wiki.php.net/rfc/class_const_visibility
    @reeze created an RFC here and I emailed internals here and didn't get any responses positive/negative.

1 files changed, 38 insertions, 4 deletions

diff --git a/Zend/zend_API.c b/Zend/zend_API.c
index 38b6426bec..fc49f3369e 100644
--- a/Zend/zend_API.c
+++ b/Zend/zend_API.c
@@ -1129,12 +1129,13 @@ ZEND_API int zend_update_class_constants(zend_class_entry *class_type) /* {{{ */
 			zend_class_entry **scope = EG(current_execute_data) ? &EG(scope) : &CG(active_class_entry);
 			zend_class_entry *old_scope = *scope;
 			zend_class_entry *ce;
+			zend_class_constant *c;
 			zval *val;
 			zend_property_info *prop_info;
 
 			*scope = class_type;
-			ZEND_HASH_FOREACH_VAL(&class_type->constants_table, val) {
-				ZVAL_DEREF(val);
+			ZEND_HASH_FOREACH_PTR(&class_type->constants_table, c) {
+				val = &c->value;
 				if (Z_CONSTANT_P(val)) {
 					if (UNEXPECTED(zval_update_constant_ex(val, 1, class_type) != SUCCESS)) {
 						return FAILURE;
@@ -3737,16 +3738,49 @@ ZEND_API int zend_declare_property_stringl(zend_class_entry *ce, const char *nam
 }
 /* }}} */
 
-ZEND_API int zend_declare_class_constant(zend_class_entry *ce, const char *name, size_t name_length, zval *value) /* {{{ */
+ZEND_API int zend_declare_class_constant_ex(zend_class_entry *ce, zend_string *name, zval *value, int access_type, zend_string *doc_comment) /* {{{ */
 {
+	zend_class_constant *c;
+
+	if (ce->ce_flags & ZEND_ACC_INTERFACE) {
+		if (access_type != ZEND_ACC_PUBLIC) {
+			zend_error_noreturn(E_COMPILE_ERROR, "Access type for interface constant %s::%s must be public", ZSTR_VAL(ce->name), ZSTR_VAL(name));
+		}
+	}
+
+	if (zend_string_equals_literal_ci(name, "class")) {
+		zend_error((ce->type == ZEND_INTERNAL_CLASS) ? E_CORE_ERROR : E_COMPILE_ERROR,
+				"A class constant must not be called 'class'; it is reserved for class name fetching");
+	}
+
+	if (ce->type == ZEND_INTERNAL_CLASS) {
+		c = pemalloc(sizeof(zend_class_constant), 1);
+	} else {
+		c = zend_arena_alloc(&CG(arena), sizeof(zend_class_constant));
+	}
+	ZVAL_COPY_VALUE(&c->value, value);
+	Z_ACCESS_FLAGS(c->value) = access_type;
+	c->doc_comment = doc_comment;
+	c->ce = ce;
 	if (Z_CONSTANT_P(value)) {
 		ce->ce_flags &= ~ZEND_ACC_CONSTANTS_UPDATED;
 	}
-	return zend_hash_str_update(&ce->constants_table, name, name_length, value) ?
+	return zend_hash_add_ptr(&ce->constants_table, name, c) ?
 		SUCCESS : FAILURE;
 }
 /* }}} */
 
+ZEND_API int zend_declare_class_constant(zend_class_entry *ce, const char *name, size_t name_length, zval *value) /* {{{ */
+{
+	int ret;
+
+	zend_string *key = zend_string_init(name, name_length, ce->type & ZEND_INTERNAL_CLASS);
+	ret = zend_declare_class_constant_ex(ce, key, value, ZEND_ACC_PUBLIC, NULL);
+	zend_string_release(key);
+	return ret;
+}
+/* }}} */
+
 ZEND_API int zend_declare_class_constant_null(zend_class_entry *ce, const char *name, size_t name_length) /* {{{ */
 {
 	zval constant;