Remove verbose code from backtrace command

Remove verbose code from backtrace command

In https://sourceware.org/ml/gdb-patches/2017-06/msg00741.html,
Pedro asks:

> Doesn't the "info verbose on" bit affect frame filters too?

The answer is that yes, it could.  However, it's not completely
effective, because the C code can't guess how many frames might need
to be unwound to satisfy the request -- a frame filter will request as
many frames as it needs.

Also, I tried removing this code from backtrace, and I think the
result is better without it.  In particular, now the expansion line
occurs just before the frame that caused the expansion, like:

    (gdb) bt no-filters
    #0  0x00007ffff576cecd in poll () from /lib64/libc.so.6
    Reading in symbols for ../../binutils-gdb/gdb/event-loop.c...done.
    #1  0x00000000007ecc33 in gdb_wait_for_event (block=1)
	at ../../binutils-gdb/gdb/event-loop.c:772
    #2  0x00000000007ec006 in gdb_do_one_event ()
	at ../../binutils-gdb/gdb/event-loop.c:347
    #3  0x00000000007ec03e in start_event_loop ()
	at ../../binutils-gdb/gdb/event-loop.c:371
    Reading in symbols for ../../binutils-gdb/gdb/main.c...done.
    #4  0x000000000086693d in captured_command_loop (
	Reading in symbols for ../../binutils-gdb/gdb/exceptions.c...done.
    data=0x0) at ../../binutils-gdb/gdb/main.c:325

So, I am proposing this patch to simply remove this code.

gdb/ChangeLog
2018-03-26  Tom Tromey  <tom@tromey.com>

	* stack.c (backtrace_command_1): Remove verbose code.