Mark unsed members with a "Z" suffix

There may be more.  There are members that are by definition
redundant or reserved and not needed, NOT what we *currently*
don't use.

I'm sure there's more...

src/hb-open-file-private.hh

@@ -110,9 +110,9 @@ typedef struct OffsetTable
   protected:
   Tag		sfnt_version;	/* '\0\001\0\00' if TrueType / 'OTTO' if CFF */
   USHORT	numTables;	/* Number of tables. */
-  USHORT	searchRange;	/* (Maximum power of 2 <= numTables) x 16 */
-  USHORT	entrySelector;	/* Log2(maximum power of 2 <= numTables). */
-  USHORT	rangeShift;	/* NumTables x 16-searchRange. */
+  USHORT	searchRangeZ;	/* (Maximum power of 2 <= numTables) x 16 */
+  USHORT	entrySelectorZ;	/* Log2(maximum power of 2 <= numTables). */
+  USHORT	rangeShiftZ;	/* NumTables x 16-searchRange. */
   TableRecord	tables[VAR];	/* TableRecord entries. numTables items */
   public:
   DEFINE_SIZE_ARRAY (12, tables);

src/hb-ot-cmap-table.hh

@@ -58,8 +58,8 @@ struct CmapSubtableFormat0
 
   protected:
   USHORT	format;		/* Format number is set to 0. */
-  USHORT	length;		/* Byte length of this subtable. */
-  USHORT	language;	/* Ignore. */
+  USHORT	lengthZ;	/* Byte length of this subtable. */
+  USHORT	languageZ;	/* Ignore. */
   BYTE		glyphIdArray[256];/* An array that maps character
 				 * code to glyph index values. */
   public:
@@ -150,11 +150,11 @@ struct CmapSubtableFormat4
   USHORT	format;		/* Format number is set to 4. */
   USHORT	length;		/* This is the length in bytes of the
 				 * subtable. */
-  USHORT	language;	/* Ignore. */
+  USHORT	languageZ;	/* Ignore. */
   USHORT	segCountX2;	/* 2 x segCount. */
-  USHORT	searchRange;	/* 2 * (2**floor(log2(segCount))) */
-  USHORT	entrySelector;	/* log2(searchRange/2) */
-  USHORT	rangeShift;	/* 2 x segCount - searchRange */
+  USHORT	searchRangeZ;	/* 2 * (2**floor(log2(segCount))) */
+  USHORT	entrySelectorZ;	/* log2(searchRange/2) */
+  USHORT	rangeShiftZ;	/* 2 x segCount - searchRange */
 
   USHORT	values[VAR];
 #if 0
@@ -217,8 +217,8 @@ struct CmapSubtableTrimmed
 
   protected:
   UINT		formatReserved;	/* Subtable format and (maybe) padding. */
-  UINT		length;		/* Byte length of this subtable. */
-  UINT		language;	/* Ignore. */
+  UINT		lengthZ;	/* Byte length of this subtable. */
+  UINT		languageZ;	/* Ignore. */
   UINT		startCharCode;	/* First character code covered. */
   ArrayOf<GlyphID, UINT>
 		glyphIdArray;	/* Array of glyph index values for character
@@ -249,9 +249,9 @@ struct CmapSubtableLongSegmented
 
   protected:
   USHORT	format;		/* Subtable format; set to 12. */
-  USHORT	reserved;	/* Reserved; set to 0. */
-  ULONG		length;		/* Byte length of this subtable. */
-  ULONG		language;	/* Ignore. */
+  USHORT	reservedZ;	/* Reserved; set to 0. */
+  ULONG		lengthZ;	/* Byte length of this subtable. */
+  ULONG		languageZ;	/* Ignore. */
   SortedArrayOf<CmapSubtableLongGroup, ULONG>
 		groups;		/* Groupings. */
   public:
@@ -381,7 +381,7 @@ struct CmapSubtableFormat14
 
   protected:
   USHORT	format;		/* Format number is set to 0. */
-  ULONG		length;		/* Byte length of this subtable. */
+  ULONG		lengthZ;	/* Byte length of this subtable. */
   SortedArrayOf<VariationSelectorRecord, ULONG>
 		record;		/* Variation selector records; sorted
 				 * in increasing order of `varSelector'. */

src/hb-ot-layout-common-private.hh

@@ -204,7 +204,7 @@ struct LangSys
     return TRACE_RETURN (c->check_struct (this) && featureIndex.sanitize (c));
   }
 
-  Offset<>	lookupOrder;	/* = Null (reserved for an offset to a
+  Offset<>	lookupOrderZ;	/* = Null (reserved for an offset to a
 				 * reordering table) */
   USHORT	reqFeatureIndex;/* Index of a feature required for this
 				 * language system--if no required features