(gdb-info-frames-custom): Reverse contrast of face for

(gdb-info-frames-custom): Reverse contrast of face for
selected frame.
(gdb-annotation-rules): Stop using frames-invalid and
breakpoints-invalid annotations. Update after post-prompt instead.
(gdb-post-prompt): Update frames and breakpoints here.
(gdb-invalidate-frame-and-assembler)
(gdb-invalidate-breakpoints-and-assembler): Remove.
(gdb-current-address): Remove.
(gdb-previous-address): New variable.
(gud-until): Extend to work in Assembler buffer
(gdb-append-to-inferior-io): Select IO buffer when there is
output.
(gdb-assembler-custom): Try to get line marker (arrow) to display
in window. Correct parsing for OS dependent output syntax of Gdb
command, where.
(gdb-frame-handler): Correct parsing for OS dependent output
syntax of Gdb command, frame.
(gdb-invalidate-assembler): Update assembler buffer correctly when
frame changes (revisited).