Fix up most but not all warnings generated by gcc-4.6 about 
dead assignments ("[-Wunused-but-set-variable]").



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@11673 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/exp-dhat/dh_main.c b/exp-dhat/dh_main.c
index 82eb941..810a289 100644
--- a/exp-dhat/dh_main.c
+++ b/exp-dhat/dh_main.c
@@ -452,7 +452,7 @@
                   Bool is_zeroed )
 {
    tl_assert(p == NULL); // don't handle custom allocators right now
-   SizeT actual_szB, slop_szB;
+   SizeT actual_szB /*, slop_szB*/;
 
    if ((SSizeT)req_szB < 0) return NULL;
 
@@ -468,9 +468,9 @@
       if (is_zeroed) VG_(memset)(p, 0, req_szB);
       actual_szB = VG_(malloc_usable_size)(p);
       tl_assert(actual_szB >= req_szB);
-      slop_szB = actual_szB - req_szB;
+      /* slop_szB = actual_szB - req_szB; */
    } else {
-      slop_szB = 0;
+      /* slop_szB = 0; */
    }
 
    // Make new HP_Chunk node, add to malloc_list