bplane: constify BPEnumInit()

bplane/bpEnum.c

@@ -50,9 +50,9 @@
  */
 void BPEnumInit(BPEnum *bpe,   /* enum to initialize */
 		BPlane *bp,
-		Rect *area,    /* search area */
+		const Rect *area,    /* search area */
 		int match,
-		char *id)      /* for debugging */
+		const char *id)      /* for debugging */
 {
   bool inside = FALSE;
   bpe->bpe_plane = bp;

bplane/bpOpaque.h

@@ -182,7 +182,7 @@ typedef struct bpenum
   BPlane *bpe_plane;           /* plane being searched */
   Rect    bpe_srchArea;        /* area being searched */
   int     bpe_match;           /* match criteria */
-  char   *bpe_id;              /* for debug */
+  const char *bpe_id;          /* for debug */
   int     bpe_subBinMinX;
   int     bpe_subBinMinY;      /* consider subbinning
 				* for bins bigger than this.

bplane/bplane.h

@@ -185,9 +185,9 @@ extern void BPEnumInit(BPEnum *bpe, /* this procedure initializes this
 				     * enumeration.
 				     */
 		       BPlane *bp, /* bplane to search */
-		       Rect *area, /* area to search */
+		       const Rect *area, /* area to search */
 		       int match,  /* see below */
-		       char *id);  /* for debugging */
+		       const char *id);  /* for debugging */
 /* match values */
 
   /* enum all elements in the bplane (area arg must be null) */