vader: fix typos in r30626

cmr=v1.7.5:ticket=trac:4053

This commit was SVN r30652.

The following SVN revision numbers were found above:
  r30626 --> open-mpi/ompi@a8867a9ca4

The following Trac tickets were found above:
  Ticket 4053 --> https://svn.open-mpi.org/trac/ompi/ticket/4053

ompi/mca/btl/vader/btl_vader_component.c

@@ -273,8 +273,8 @@ static mca_btl_base_module_t **mca_btl_vader_component_init (int *num_btls,
         mca_btl_vader_component.segment_size = (2 << 20);
     }
 
-    if (mca_btl_vader_component.segment_size > (1 << MCA_BTL_VADER_OFFSET_BITS)) {
-        mca_btl_vader_component.segment_size = 2 << MCA_BTL_VADER_OFFSET_BITS;
+    if (mca_btl_vader_component.segment_size > (1ul << MCA_BTL_VADER_OFFSET_BITS)) {
+        mca_btl_vader_component.segment_size = 2ul << MCA_BTL_VADER_OFFSET_BITS;
     }
 
 #if OMPI_BTL_VADER_HAVE_XPMEM