sid debugger interface extension: step out-of-range packet support

["Frank Ch. Eigler" <fche at redhat dot com>]

Hi -

A small amount of new code in sid/include and sid/component/gdb
now allows gdb's "step out-of-range" packet ('e'/'E') to work with
all sid-based simulator targets.  This packet makes remote debugging
potentially significantly faster, because it can replace a sequence of
instruction single-step packets with just one new packet.  This finally
exercises J.T. Conklin's gdb-side extensions from roughly a year ago.

There is a gdb bug that is exposed by this support.  If a breakpoint
placed on the current instruction, and another one on the next
source line, then letting gdb "step" will stop at the next line, but
won't let gdb realize that the second breakpoint was hit.  (This is
because gdb never inserted the breakpoints in gdb/infrun.c's proceed(),
being unaware that remote_resume() meant something other than stepi.)
This looks like this is a minor problem, but just in case, support for
the packet may be forced off from the gdb side and/or from the sid side.

- FChE