* progmodes/gdb-mi.el (gdb-breakpoints-buffer-name)

* progmodes/gdb-mi.el (gdb-breakpoints-buffer-name)
(gdb-locals-buffer-name, gdb-registers-buffer-name)
(gdb-memory-buffer-name, gdb-stack-buffer-name): Do not switch
to (gud-comint-buffer) in *-buffer-name functions
because (gdb-get-target-string) already does that.
(gdb-locals-handler-custom, gdb-registers-handler-custom)
(gdb-changed-registers-handler): Rewritten without regexps.