Change ZEND_ALTERNATIVE_ARRAY_SYNTAX value so it doesn't conflict with ZEND_DIM_IS

This was causing the constant_expressions_coalesce.phpt test to fail.

Author: theodorejb

Zend/zend_compile.h

@@ -992,7 +992,7 @@ static zend_always_inline int zend_check_arg_send_type(const zend_function *zf,
 #define ZEND_ARRAY_SIZE_SHIFT		2
 
 /* Array/string access syntax with curly braces is used */
-#define ZEND_ALTERNATIVE_ARRAY_SYNTAX			1
+#define ZEND_ALTERNATIVE_ARRAY_SYNTAX			2
 
 /* Attribute for ternary inside parentheses */
 #define ZEND_PARENTHESIZED_CONDITIONAL 1