Support GCC's -Wconversion -Wfloat-conversion -Warith-conversion -Wsign-conversion warnings.

test/expand_bwd_test_allocator.hpp

@@ -79,7 +79,7 @@ class expand_bwd_test_allocator
    {  typedef expand_bwd_test_allocator<T2>   other;   };
 
    //!Constructor from the segment manager. Never throws
-   expand_bwd_test_allocator(T *buffer, size_type sz, difference_type offset)
+   expand_bwd_test_allocator(T *buffer, size_type sz, size_type offset)
       : mp_buffer(buffer), m_size(sz)
       , m_offset(offset),  m_allocations(0){ }
 
@@ -171,7 +171,7 @@ class expand_bwd_test_allocator
 
    pointer           mp_buffer;
    size_type         m_size;
-   difference_type   m_offset;
+   size_type         m_offset;
    char              m_allocations;
 };