Free all static memory upon exit

src/hb-shape.cc

diff --git a/src/hb-shape.cc b/src/hb-shape.cc
index 986dd70..9e4469d 100644
--- a/src/hb-shape.cc
+++ b/src/hb-shape.cc
@@ -60,8 +60,8 @@
 };
 #undef HB_SHAPER_IMPLEMENT
 
-static class static_shaper_list_t {
-  public:
+static struct static_shaper_list_t
+{
   static_shaper_list_t (void)
   {
     char *env = getenv ("HB_SHAPER_LIST");