* gdb.base/callfuncs.exp: call runto_main instead of runto main.

    * gdb.base/callfuncs.exp: call runto_main instead of runto main.
        runto_main is a proc in gdb.exp that will do 'step' for target use
        stubs.
        * gdb.base/exprs.exp: ditto.
        * gdb.base/interrupt.exp: ditto.
        * gdb.base/opaque.exp: ditto.
        * gdb.base/printcmds.exp: ditto.
        * gdb.base/ptype.exp: ditto.
        * gdb.base/scope.exp: ditto.
        * gdb.base/setvar.exp: ditto.
        * gdb.base/signals.exp: ditto.
        * gdb.base/twice.exp: ditto.
        * gdb.base/break.exp: no run and hit main for stubs. Change line
        numbers for breakpoints and info breakpoint.
        * gdb.base/break.c: Add #ifdef usestubs for set_debug_traps() and
        breakpoint().
        * gdb.base/callfuncs.c: ditto.
        * gdb.base/exprs: ditto.
        * gdb.base/interrupt.c: ditto.
        * gdb.base/opaque0.c: ditto.
        * gdb.base/printcmds.c: ditto.
        * gdb.base/ptype.c: ditto.
        * gdb.base/scope0.c: ditto.
        * gdb.base/setvar.c: ditto.
        * gdb.base/signals.c: ditto.
        * gdb.base/twice.c: ditto.