Remove unused PointerHolder interface

Also fix a bug resulting from incorrect use of PointerHolder because
of this unused parameter.

ChangeLog

@@ -1,3 +1,16 @@
+2017-08-10  Jay Berkenbilt  <ejb@ql.org>
+
+	* Remove unused "tracing" parameter from PointerHolder's
+	(T*, bool) constructor. This change breaks source code
+	compatibility, but since this argument to PointerHolder has not
+	used for a long time and the presence of a boolean parameter in
+	the primary constructor makes it too easy to use that by mistake
+	when trying to use PointerHolder for arrays, it seems like it's
+	finally time to take it out. If you have a compile error because
+	of this change, please check to see whether you intended to use
+	the (bool, T*) version of the constructor instead. If not, just
+	remove the second parameter.
+
 2017-08-05  Jay Berkenbilt  <ejb@ql.org>
 
 	* Add --single-pages option to cause output to be written to a

include/qpdf/PointerHolder.hh

@@ -69,8 +69,7 @@ class PointerHolder
     };
 
   public:
-    // "tracing" is not used but is kept for interface backward compatbility
-    PointerHolder(T* pointer = 0, bool tracing = false)
+    PointerHolder(T* pointer = 0)
 	{
 	    this->init(new Data(pointer, false));
 	}

qpdf/qpdf.cc

@@ -1103,7 +1103,7 @@ static void read_args_from_file(char const* filename,
          iter != lines.end(); ++iter)
     {
         new_argv.push_back(
-            PointerHolder<char>(QUtil::copy_string((*iter).c_str()), true));
+            PointerHolder<char>(true, QUtil::copy_string((*iter).c_str())));
     }
 }