build: resolve build failure of zendfake

/usr/bin/ld: ./.libs/libmapi4zf.so: undefined reference to `zend_fetch_debug_backtrace'
/usr/bin/ld: ./.libs/libmapi4zf.so: undefined reference to `zend_trace_to_string'

Author: jengelh

tests/zendfake.cpp

@@ -51,6 +51,7 @@ php_info_print_table_end,
 php_info_print_table_row,
 php_info_print_table_start,
 php_sprintf,
+zend_fetch_debug_backtrace,
 zend_fetch_resource,
 zend_get_constant,
 zend_hash_find,
@@ -69,9 +70,10 @@ zend_register_ini_entries,
 zend_register_ini_entries_ex,
 zend_register_list_destructors_ex,
 zend_register_resource,
+zend_throw_exception,
+zend_trace_to_string,
 zend_unregister_ini_entries,
 zend_unregister_ini_entries_ex,
-zend_throw_exception,
 zval_get_double_func,
 zval_get_long_func,
 zval_get_string_func,