[config] Add HB_NO_OT_TAG

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

src/hb-config.hh

@@ -124,6 +124,7 @@
 #ifdef HB_NO_OT
 #define HB_NO_OT_FONT
 #define HB_NO_OT_LAYOUT
+#define HB_NO_OT_TAG
 #define HB_NO_OT_SHAPE
 #endif
 

src/hb-ot-layout.cc

@@ -32,6 +32,10 @@
 
 #ifndef HB_NO_OT_LAYOUT
 
+#ifdef HB_NO_OT_TAG
+#error "Cannot compile hb-ot-layout.cc with HB_NO_OT_TAG."
+#endif
+
 #include "hb-open-type.hh"
 #include "hb-ot-layout.hh"
 #include "hb-ot-face.hh"

src/hb-ot-tag.cc

@@ -28,6 +28,8 @@
 
 #include "hb.hh"
 
+#ifndef HB_NO_OT_TAG
+
 
 /* hb_script_t */
 
@@ -548,3 +550,6 @@ main ()
 }
 
 #endif
+
+
+#endif

src/hb-uniscribe.cc

@@ -28,6 +28,10 @@
 
 #ifdef HAVE_UNISCRIBE
 
+#ifdef HB_NO_OT_TAG
+#error "Cannot compile 'uniscribe' shaper with HB_NO_OT_TAG."
+#endif
+
 #include "hb-shaper-impl.hh"
 
 #include <windows.h>