* breakpoint.c (bpstat_do_actions): Use a cleanup to restore

* breakpoint.c (bpstat_do_actions):  Use a cleanup to restore
executing_breakpoint_commands if we are interrupted by error.
* coffread.c (init_lineno):  Avoid problem with zero-sized linetab
versus malloc/free.  From: john@labtam.labtam.oz.au (John Carey).
* core.c (solib_add_stub, core_open):  Call SOLIB_ADD inside a
catch_errors() so we can setup the frame regardless of whether
the shared libs work.
* ieee-float.c (double_to_ieee_extended):  Get exponent from
right place in little-endian systems.  From John Carey.