Use FWORD and UFWORD when it makes sense

I had forgotten about those types.

src/hb-ot-glyf-table.hh

@@ -90,10 +90,10 @@ struct glyfGlyphHeader
 					 * greater than or equal to zero,
 					 * this is a simple glyph; if negative,
 					 * this is a composite glyph. */
-  SHORT		xMin;			/* Minimum x for coordinate data. */
-  SHORT		yMin;			/* Minimum y for coordinate data. */
-  SHORT		xMax;			/* Maximum x for coordinate data. */
-  SHORT		yMax;			/* Maximum y for coordinate data. */
+  FWORD		xMin;			/* Minimum x for coordinate data. */
+  FWORD		yMin;			/* Minimum y for coordinate data. */
+  FWORD		xMax;			/* Maximum x for coordinate data. */
+  FWORD		yMax;			/* Maximum y for coordinate data. */
 
   DEFINE_SIZE_STATIC (10);
 };

src/hb-ot-hmtx-table.hh

@@ -44,8 +44,8 @@ namespace OT {
 
 struct LongMetric
 {
-  USHORT	advance; /* Advance width/height. */
-  SHORT		lsb; /* Leading (left/top) side bearing. */
+  UFWORD	advance; /* Advance width/height. */
+  FWORD		lsb; /* Leading (left/top) side bearing. */
   public:
   DEFINE_SIZE_STATIC (4);
 };
@@ -74,7 +74,7 @@ struct _mtx
 					 * be in the array, but that entry is
 					 * required. The last entry applies to
 					 * all subsequent glyphs. */
-  SHORT		leadingBearingX[VAR];	/* Here the advance is assumed
+  FWORD		leadingBearingX[VAR];	/* Here the advance is assumed
 					 * to be the same as the advance
 					 * for the last entry above. The
 					 * number of entries in this array is