[style] New experimental API, hb_style_get_value

Searches variation axes of a hb_font_t object for a specific axis first,
if not set, then tries to get default style values from different
tables of the font.
diff --git a/src/hb-config.hh b/src/hb-config.hh
index 07659fa..fc8d424 100644
--- a/src/hb-config.hh
+++ b/src/hb-config.hh
@@ -76,7 +76,7 @@
 #define HB_NO_SETLOCALE
 #define HB_NO_OT_FONT_GLYPH_NAMES
 #define HB_NO_OT_SHAPE_FRACTIONS
-#define HB_NO_STAT
+#define HB_NO_STYLE
 #define HB_NO_SUBSET_LAYOUT
 #define HB_NO_VAR
 #endif