one(s) there should be removed when we have to step over one. Support
breakpoints that don't have to be removed to step over them.
-Speed up watchpoints by not single-stepping them, but do something
-faster like single-line execution. Speed them up tremendously on
-machines that have watchpoint registers.
+Speed up watchpoints by using debug registers, page table diddling (on
+SunOS4, can call mprotect() in the inferior; on other machines can do
+something simpler), etc.
Update gdbint.texinfo to include doc on the directory structure and
the various tricks of building gdb.