Change zend_ast_kind and zend_ast_attr from uint16_t to uint32_t

The zend_ast_attr type was defined as uint16_t, limiting it to 16 bits,
but it's used to store ZEND_ACC_* flags which can use bits up to 31:

- ZEND_ACC_OVERRIDE = (1 << 28)
- ZEND_ACC_ENUM = (1 << 28)
- ZEND_ACC_STRICT_TYPES = (1U << 31)

While current code doesn't appear to assign these high-bit flags to
ast->attr fields, the type mismatch creates a potential bug where any
future code attempting to store ZEND_ACC flags with bits 16-31 would
have those bits silently truncated to zero.

Additionally, several functions (zend_ast_create_va, zend_ast_create_ex_*,
etc.) accept uint32_t or zend_ast_attr parameters before assigning to the
attr field, creating a truncation point at line 821 in zend_language_parser.y
where zend_modifier_list_to_flags() returns uint32_t.

This change:
1. Changes zend_ast_kind typedef from uint16_t to uint32_t
2. Changes zend_ast_attr typedef from uint16_t to uint32_t

Extending kind to uint32_t maintains natural alignment without requiring
explicit padding fields. The structure sizes remain unchanged. Padding
was already present implicitly due to alignment.

Author: withinboredom

Zend/zend_ast.h

@@ -182,8 +182,8 @@ enum _zend_ast_kind {
 	ZEND_AST_PARAM = 6 << ZEND_AST_NUM_CHILDREN_SHIFT,
 };
 
-typedef uint16_t zend_ast_kind;
-typedef uint16_t zend_ast_attr;
+typedef uint32_t zend_ast_kind;
+typedef uint32_t zend_ast_attr;
 
 struct _zend_ast {
 	zend_ast_kind kind; /* Type of the node (ZEND_AST_* enum constant) */