Followup to r11619: more tidying up w.r.t. the renaming of 
'struct _Thr :: opaque' to 'struct _Thr :: hgthread'.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@11623 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/helgrind/libhb.h b/helgrind/libhb.h
index 39711b5..ea8fcb2 100644
--- a/helgrind/libhb.h
+++ b/helgrind/libhb.h
@@ -131,8 +131,8 @@
 
 /* Get and set the hgthread (pointer to corresponding Thread
    structure). */
-void* libhb_get_Thr_hgthread ( Thr* );
-void  libhb_set_Thr_hgthread ( Thr*, void* );
+Thread* libhb_get_Thr_hgthread ( Thr* );
+void    libhb_set_Thr_hgthread ( Thr*, Thread* );
 
 /* Low level copy of shadow state from [src,src+len) to [dst,dst+len).
    Overlapping moves are checked for and asserted against. */