Bug 77732 - Fix unused typedef warning for ASSERT_STATIC with GCC 4.8

src/hb-private.hh

diff --git a/src/hb-private.hh b/src/hb-private.hh
index 370a36a..1a1926d 100644
--- a/src/hb-private.hh
+++ b/src/hb-private.hh
@@ -146,7 +146,7 @@
 #define HB_STMT_START do
 #define HB_STMT_END   while (0)
 
-#define _ASSERT_STATIC1(_line, _cond)	typedef int _static_assert_on_line_##_line##_failed[(_cond)?1:-1]
+#define _ASSERT_STATIC1(_line, _cond)	HB_UNUSED typedef int _static_assert_on_line_##_line##_failed[(_cond)?1:-1]
 #define _ASSERT_STATIC0(_line, _cond)	_ASSERT_STATIC1 (_line, (_cond))
 #define ASSERT_STATIC(_cond)		_ASSERT_STATIC0 (__LINE__, (_cond))