(gdb-info-breakpoints-custom, gdb-assembler-custom):

(gdb-info-breakpoints-custom, gdb-assembler-custom):
Put string associated with breakpoint at start of line so that it
is always visible.
(gdb-display-source-buffer): Display assembler during execution,
when requested.
(gud-menu-map): Add a toggle button to menubar for
gdb-many-windows.
(gdb-many-windows): Define explicitly as a function and a variable
(formerly as a minor mode). These need to be global so layout can
be reset from any buffer.
(gdb-assembler-mode): Keep fringe outside margin as the overlay
arrow is not used for assembler.