Fix breakage in GEODEBUG debug code.

LINE doesn't have an "m" field (anymore anyway).  Also fix unportable
assumption that %x can print the result of pointer subtraction.

In passing, improve single_decode() in minor ways:
* Remove unnecessary leading-whitespace skip (strtod does that already).
* Make GEODEBUG message more intelligible.
* Remove entirely-useless test to see if strtod returned a silly pointer.
* Don't bother computing trailing-whitespace skip unless caller wants
  an ending pointer.

This has been broken since 261c7d4b.
Although it's only debug code, might as well fix the 9.4 branch too.

src/backend/utils/adt/geo_ops.c

@@ -128,19 +128,19 @@ single_decode(char *str, float8 *x, char **s)
 	if (!PointerIsValid(str))
 		return FALSE;
 
-	while (isspace((unsigned char) *str))
-		str++;
 	*x = strtod(str, &cp);
+
 #ifdef GEODEBUG
-	printf("single_decode- (%x) try decoding %s to %g\n", (cp - str), str, *x);
+	printf("single_decode- decoded first %d chars of \"%s\" to %g\n",
+		   (int) (cp - str), str, *x);
 #endif
-	if (cp <= str)
-		return FALSE;
-	while (isspace((unsigned char) *cp))
-		cp++;
 
 	if (s != NULL)
+	{
+		while (isspace((unsigned char) *cp))
+			cp++;
 		*s = cp;
+	}
 
 	return TRUE;
 }	/* single_decode() */
@@ -2901,8 +2901,8 @@ close_ps(PG_FUNCTION_ARGS)
 		result = point_copy(&lseg->p[!yh]);		/* below the lseg, take lower
 												 * end pt */
 #ifdef GEODEBUG
-		printf("close_ps below: tmp A %f  B %f   C %f    m %f\n",
-			   tmp->A, tmp->B, tmp->C, tmp->m);
+		printf("close_ps below: tmp A %f  B %f   C %f\n",
+			   tmp->A, tmp->B, tmp->C);
 #endif
 		PG_RETURN_POINT_P(result);
 	}
@@ -2913,8 +2913,8 @@ close_ps(PG_FUNCTION_ARGS)
 		result = point_copy(&lseg->p[yh]);		/* above the lseg, take higher
 												 * end pt */
 #ifdef GEODEBUG
-		printf("close_ps above: tmp A %f  B %f   C %f    m %f\n",
-			   tmp->A, tmp->B, tmp->C, tmp->m);
+		printf("close_ps above: tmp A %f  B %f   C %f\n",
+			   tmp->A, tmp->B, tmp->C);
 #endif
 		PG_RETURN_POINT_P(result);
 	}
@@ -2925,8 +2925,8 @@ close_ps(PG_FUNCTION_ARGS)
 	 */
 	tmp = line_construct_pm(pt, invm);
 #ifdef GEODEBUG
-	printf("close_ps- tmp A %f  B %f   C %f    m %f\n",
-		   tmp->A, tmp->B, tmp->C, tmp->m);
+	printf("close_ps- tmp A %f  B %f   C %f\n",
+		   tmp->A, tmp->B, tmp->C);
 #endif
 	result = interpt_sl(lseg, tmp);
 	Assert(result != NULL);