the case where your program has had its heap corrupted and is very nearly about to crash,
and so when an assert triggers it crashes on the code that constructs the error
message because the heap is hosed.  Thus preventing you from hitting a break point
on dlib_assert_breakpoint().  So this change mitigates that.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402580