[matcher] Simplify syllable initialization

src/hb-ot-layout-gsubgpos.hh

diff --git a/src/hb-ot-layout-gsubgpos.hh b/src/hb-ot-layout-gsubgpos.hh
index a15bc86..8ba555c 100644
--- a/src/hb-ot-layout-gsubgpos.hh
+++ b/src/hb-ot-layout-gsubgpos.hh
@@ -411,9 +411,7 @@
 	     ignore_zwnj (false),
 	     ignore_zwj (false),
 	     mask (-1),
-#define arg1(arg) (arg) /* Remove the macro to see why it's needed! */
-	     syllable arg1(0),
-#undef arg1
+	     syllable {0},
 	     match_func (nullptr),
 	     match_data (nullptr) {}