[config] Add HB_NO_SHAPER

Don't know who would want when why.  But makes sense to have.

src/hb-shaper-list.hh

@@ -28,6 +28,9 @@
 #define HB_SHAPER_LIST_HH
 #endif /* HB_SHAPER_LIST_HH */ /* Dummy header guards */
 
+#ifndef HB_NO_SHAPER
+
+
 /* v--- Add new shapers in the right place here. */
 
 #ifdef HAVE_GRAPHITE2
@@ -52,3 +55,6 @@ HB_SHAPER_IMPLEMENT (coretext)
 #ifndef HB_NO_FALLBACK_SHAPE
 HB_SHAPER_IMPLEMENT (fallback) /* <--- This should be last. */
 #endif
+
+
+#endif

src/hb-shaper.cc

@@ -34,7 +34,9 @@ static const hb_shaper_entry_t all_shapers[] = {
 #include "hb-shaper-list.hh"
 #undef HB_SHAPER_IMPLEMENT
 };
+#ifndef HB_NO_SHAPER
 static_assert (0 != ARRAY_LENGTH_CONST (all_shapers), "No shaper enabled.");
+#endif
 
 #if HB_USE_ATEXIT
 static void free_static_shapers ();