[Bug 21502] New: missing valgrind annotation in mark_block_free

http://bugs.winehq.org/show_bug.cgi?id=21502

Summary: missing valgrind annotation in mark_block_free
           Product: Wine
           Version: 1.1.37
          Platform: x86
        OS/Version: Linux
            Status: NEW
          Keywords: download, patch, source
          Severity: normal
          Priority: P2
         Component: ntdll
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]

Running any test with +heap and valgrind, e.g.

WINEDEBUG=+heap WINETEST_WRAPPER=valgrind make atom.ok

generates warnings like this:

Invalid write of size 4 
   at mark_block_free (heap.c:175)
   by heap_set_debug_flags (heap.c:1382)
   by RtlCreateHeap (heap.c:1446)
   by virtual_init (virtual.c:1354)
   by thread_init (thread.c:203)
   by __wine_process_init (loader.c:2850)
   by wine_init (loader.c:711)
   by main (main.c:218)
 Address 0xbfa60138 is not stack'd, malloc'd or (recently) free'd

This is due to a missing annotation in mark_block_free.
The attached patch makes the warning go away.