Try fixing build for platforms that have no visibility attributes

src/hb-private.hh

@@ -124,6 +124,7 @@ extern "C" void  hb_free_impl(void *ptr);
 #  define HB_INTERNAL __attribute__((__visibility__("hidden")))
 # else
 #  define HB_INTERNAL
+#  define HB_NO_VISIBILITY 1
 # endif
 #endif
 

src/hb-subset.cc

@@ -35,7 +35,9 @@
 #include "hb-ot-glyf-table.hh"
 
 
+#ifndef HB_NO_VISIBILITY
 const void * const OT::_hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
+#endif
 
 
 struct hb_subset_profile_t {

src/main.cc

@@ -37,7 +37,9 @@
 
 using namespace OT;
 
+#ifndef HB_NO_VISIBILITY
 const void * const OT::_hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
+#endif
 
 int
 main (int argc, char **argv)