This patch makes breakpoint_re_set_one handle pending
breakpoints and eliminates resolve_pending_breakpoints.
As a side effect, when a pending breakpoint is resolved,
it no longer changes number. The real purpose of this
patch is that with multiple breakpoints, breakpoint_re_set_one
gets to update the set of locations of a breakpoint, and this
will automatically handle pending breakpoints anyway. OK?

- Volodya