gdb.base/breakpoint-in-ro-region.exp regression on sss targets (PR gdb/22583)

gdb.base/breakpoint-in-ro-region.exp regression on sss targets (PR gdb/22583)

As Maciej reported at
<https://sourceware.org/ml/gdb-patches/2017-12/msg00212.html>, this
commit:

 commit d930703d68ae160ddfe8ebe5fdcf416fb6090e1e
 Date: Thu Nov 16 18:44:43 2017 +0000
 Subject: Don't ever Quit out of resume

caused regressions on software single-set targets, specifically:

 FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw off: single-step breakpoint is not left behind
 FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw on: single-step breakpoint is not left behind
 FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted on: auto-hw off: step in ro region (cannot insert hw break)
 FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted on: auto-hw off: single-step breakpoint is not left behind
 FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted on: auto-hw on: single-step breakpoint is not left behind

and indeed detailed logs indicate a breakpoint is left lingering, e.g.:

 (gdb) PASS: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw off: step in ro region (cannot insert sw break)
 maint info breakpoints 0
 Num     Type           Disp Enb Address    What
 0       sw single-step keep y   0x00400774 in main at [...]/gdb/testsuite/gdb.base/breakpoint-in-ro-region.c:24 inf 1 thread 1
	 stop only in thread 1
 (gdb) FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw off: single-step breakpoint is not left behind

vs:

 (gdb) PASS: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw off: step in ro region (cannot insert sw break)
 maint info breakpoints 0
 No breakpoint or watchpoint matching '0'.
 (gdb) PASS: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw off: single-step breakpoint is not left behind

as at commit d930703d68ae^.

Before commit d930703d68ae, we had a cleanup installed in 'resume'
that would delete single-step breakpoints on error:

  /* Resuming.  */

  /* Things to clean up if we QUIT out of resume ().  */
  static void
  resume_cleanups (void *ignore)
  {
    if (!ptid_equal (inferior_ptid, null_ptid))
     delete_single_step_breakpoints (inferior_thread ());

    normal_stop ();
  }

That whole function was removed by d930703d68ae mainly to eliminate
the normal_stop call:

~~~~
    Note that the exception called from within resume ends up calling
    normal_stop via resume_cleanups.  That's very borked though, because
    normal_stop is going to re-handle whatever was the last reported
    event, possibly even re-running a hook stop...
~~~~

But as the regression shows, removing resume_cleanups completely went
a bit too far, as the delete_single_step_breakpoints call is still
necessary.

So fix the regression by reinstating the
delete_single_step_breakpoints call on error.  However, since we're
trying to eliminate cleanups, restore it in a different form (using
TRY/CATCH).

Tested on x86-64 GNU/Linux both top of master and on top of a series
that implements software single-step on x86.

gdb/ChangeLog:
2018-01-11  Pedro Alves  <palves@redhat.com>

	PR gdb/22583
	* infrun.c (resume): Rename to ...
	(resume_1): ... this.
	(resume): Reimplement as wrapper around resume_1.