PHP 8.0: define TSRMLS* macros as no-op

The TSRM* macros are no-op since PHP 7.0. PHP 8.0 drops them at all.
Define them as no-op in our code when building against PHP 8 and newer
to overcome a build fail. See [1] and [2] (1.c) for details.

Those macros could be removed from the code entirely (both definitions
and usages), since we support PHP 7.0+. It is to be done later.

[1]: https://wiki.php.net/rfc/native-tls
[2]: https://github.com/php/php-src/blob/php-8.0.18RC1/UPGRADING.INTERNALS

Part of tarantool#171

Author: Mikhail Galanin

src/php_tarantool.h

@@ -29,6 +29,13 @@
 #  define smart_string_free_ex(...) smart_str_free_ex(__VA_ARGS__)
 #endif
 
+#if PHP_VERSION_ID >= 80000
+/* These macroses were removed in PHP 8. */
+#  define TSRMLS_CC
+#  define TSRMLS_DC
+#  define TSRMLS_FETCH()
+#endif /* PHP_VERSION_ID >= 80000 */
+
 #if PHP_VERSION_ID < 70300
 #  define GC_SET_REFCOUNT(p, rc) do { \
 	GC_REFCOUNT((p)) = (rc);      \