[OB PATCH][testsuite] Fix regexp in list-thread-groups-available.exp

[Tom de Vries <tdevries at suse dot de>]

Hi,

I ran into a gdb.mi/list-thread-groups-available.exp failure:
...
Running gdb/testsuite/gdb.mi/list-thread-groups-available.exp ...
FAIL: gdb.mi/list-thread-groups-available.exp:
        list available thread groups (unexpected output)
PASS: gdb.mi/list-thread-groups-available.exp:
        list available thread groups with filter
...
When doing an experiment of running it 100 times in a row, the failure
reproduced 3 times.

Analyzing the original failure led to insufficient quoting of square brackets
in a regexp.  This patch fixes the regexp, which resulted in 0 failures in a
100-in-a-row run.

Tested on x86_64-linux.

Committed as obvious.

Thanks,
- Tom

[gdb/testsuite] Fix regexp in list-thread-groups-available.exp

2018-07-19  Tom de Vries  <tdevries@suse.de>

	* gdb.mi/list-thread-groups-available.exp (cores_re): Fix quoting in
	regular	expression.

---
 gdb/testsuite/gdb.mi/list-thread-groups-available.exp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.mi/list-thread-groups-available.exp b/gdb/testsuite/gdb.mi/list-thread-groups-available.exp
index 7fd0ea223a..c4dab2a2c3 100644
--- a/gdb/testsuite/gdb.mi/list-thread-groups-available.exp
+++ b/gdb/testsuite/gdb.mi/list-thread-groups-available.exp
@@ -45,7 +45,7 @@ set id_re "id=\"$decimal\""
 set type_re "type=\"process\""
 set description_re "description=\"$string_re\""
 set user_re "user=\"$string_re\""
-set cores_re "cores=\[\"$decimal\"(,\"$decimal\")*\]"
+set cores_re "cores=\\\[\"$decimal\"(,\"$decimal\")*\\\]"
 
 # List all available processes.
 set process_entry_re "{${id_re},${type_re}(,$description_re)?(,$user_re)?(,$cores_re)?}"