Fix compile warnings for ragel-generated machines

src/hb-ot-shape-complex-indic-machine.rl

@@ -103,7 +103,7 @@ main := |*
 static void
 find_syllables (hb_buffer_t *buffer)
 {
-  unsigned int p, pe, eof, ts HB_UNUSED, te, act;
+  unsigned int p, pe, eof, ts HB_UNUSED, te HB_UNUSED, act HB_UNUSED;
   int cs;
   hb_glyph_info_t *info = buffer->info;
   %%{

src/hb-ot-shape-complex-myanmar-machine.rl

@@ -102,7 +102,7 @@ main := |*
 static void
 find_syllables (hb_buffer_t *buffer)
 {
-  unsigned int p, pe, eof, ts HB_UNUSED, te, act;
+  unsigned int p, pe, eof, ts HB_UNUSED, te HB_UNUSED, act HB_UNUSED;
   int cs;
   hb_glyph_info_t *info = buffer->info;
   %%{

src/hb-ot-shape-complex-sea-machine.rl

@@ -79,7 +79,7 @@ main := |*
 static void
 find_syllables (hb_buffer_t *buffer)
 {
-  unsigned int p, pe, eof, ts HB_UNUSED, te, act;
+  unsigned int p, pe, eof, ts HB_UNUSED, te HB_UNUSED, act HB_UNUSED;
   int cs;
   hb_glyph_info_t *info = buffer->info;
   %%{