Bug#12856915 VALGRIND FAILURE IN FILESORT/CREATE_SORT_INDEX

Suppress the known warnings generated by filesort().

The real fix belongs to worklog 1509:
Pack values of non-sorted fields in the sort buffer
(which is basically the same issue, but in an optimization context:
 We are writing the entire sort buffer to disk, 
 including un-used space for varchar columns.)

mysql-test/valgrind.supp

@@ -791,3 +791,37 @@
    fun:fil_delete_tablespace
    fun:row_drop_table_for_mysql
 }
+
+{
+   Bug#12856915 VALGRIND FAILURE IN FILESORT/CREATE_SORT_INDEX / one
+   Memcheck:Param
+   write(buf)
+   obj:*/libpthread*.so
+   fun:my_write
+   fun:my_b_flush_io_cache
+   fun:_my_b_write
+   fun:_ZL10write_keysP13st_sort_paramPPhjP11st_io_cacheS4_
+   fun:_ZL13find_all_keysP13st_sort_paramP10SQL_SELECTPPhP11st_io_cacheS6_S6_
+   fun:_Z8filesortP3THDP8st_tableP13st_sort_fieldjP10SQL_SELECTybPy
+}
+
+{
+   Bug#12856915 VALGRIND FAILURE IN FILESORT/CREATE_SORT_INDEX / two
+   Memcheck:Param
+   write(buf)
+   obj:*/libpthread*.so
+   fun:my_write
+   fun:my_b_flush_io_cache
+   fun:_Z15merge_many_buffP13st_sort_paramPhP10st_buffpekPjP11st_io_cache
+   fun:_Z8filesortP3THDP8st_tableP13st_sort_fieldjP10SQL_SELECTybPy
+}
+
+{
+   Bug#12856915 VALGRIND FAILURE IN FILESORT/CREATE_SORT_INDEX / three
+   Memcheck:Param
+   write(buf)
+   obj:*/libpthread*.so
+   fun:my_write
+   fun:my_b_flush_io_cache
+   fun:_Z8filesortP3THDP8st_tableP13st_sort_fieldjP10SQL_SELECTybPy
+}

sql/filesort.cc

@@ -959,21 +959,10 @@ static void make_sortkey(register SORTPARAM *param,
       if (addonf->null_bit && field->is_null())
       {
         nulls[addonf->null_offset]|= addonf->null_bit;
-#ifdef HAVE_purify
-	bzero(to, addonf->length);
-#endif
       }
       else
       {
-#ifdef HAVE_purify
-        uchar *end= field->pack(to, field->ptr);
-	uint length= (uint) ((to + addonf->length) - end);
-	DBUG_ASSERT((int) length >= 0);
-	if (length)
-	  bzero(end, length);
-#else
         (void) field->pack(to, field->ptr);
-#endif
       }
       to+= addonf->length;
     }