Remove public enum names again

As was reported to me, glib-mkenum does not understand named enums,
so remove for now.

src/hb-blob.h

@@ -36,7 +36,7 @@
 HB_BEGIN_DECLS
 
 
-typedef enum _hb_memory_mode_t {
+typedef enum {
   HB_MEMORY_MODE_DUPLICATE,
   HB_MEMORY_MODE_READONLY,
   HB_MEMORY_MODE_WRITABLE,

src/hb-common.h

@@ -99,7 +99,7 @@ hb_tag_t hb_tag_from_string (const char *str, int len);
 
 /* hb_direction_t */
 
-typedef enum _hb_direction_t {
+typedef enum {
   HB_DIRECTION_INVALID = 0,
   HB_DIRECTION_LTR = 4,
   HB_DIRECTION_RTL,
@@ -140,7 +140,7 @@ hb_language_get_default (void);
 
 /* hb_unicode_general_category_t */
 
-typedef enum _hb_unicode_general_category_t
+typedef enum
 {
   HB_UNICODE_GENERAL_CATEGORY_CONTROL,			/* Cc */
   HB_UNICODE_GENERAL_CATEGORY_FORMAT,			/* Cf */
@@ -179,7 +179,7 @@ typedef enum _hb_unicode_general_category_t
 
 /* http://unicode.org/iso15924/ */
 /* http://goo.gl/x9ilM */
-typedef enum _hb_script_t
+typedef enum
 {
   /* Unicode-1.1 additions */
   HB_SCRIPT_COMMON			= HB_TAG ('Z','y','y','y'),

src/hb-ot-layout-private.hh

@@ -44,7 +44,7 @@
 #define props_cache() var1.u16[1] /* glyph_props cache */
 
 /* XXX cleanup */
-typedef enum _hb_ot_layout_glyph_class_t {
+typedef enum {
   HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED	= 0x0001,
   HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH	= 0x0002,
   HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE	= 0x0004,