[PATCH v2] Fix random dejagnu test abort with simulator target

[Bernd Edlinger <bernd.edlinger@hotmail.de>]

This is probably a dejagnu issue with the gdb testsuite
when a simulator target is used.  I observed random
testrun aborts with dejagnu 1.6.2-1 from ubuntu 20.04
The problem starts when the test case gdb.base/sigwinch-notty.exp
tries to execute "sleep", although that is impossible with a
simulator.  And for unknown reason the test case completes
(with errors) before the "after 1000" block is run.

Then in a totally different test this happens with 50% likelihood:

ERROR: (DejaGnu) proc "bgerror {can't read "gdb_pid": no such variable}" does not exist.
The error code is TCL LOOKUP COMMAND bgerror
The info on the error is:
invalid command name "bgerror"
    while executing
"::tcl_unknown bgerror {can't read "gdb_pid": no such variable}"
    ("uplevel" body line 1)
    invoked from within
"uplevel 1 ::tcl_unknown $args"

                === gdb Summary ===

 # of expected passes            30815
 # of unexpected failures        241
 # of expected failures          3
 # of known failures             23
 # of unresolved testcases       241
 # of untested testcases         96
 # of unsupported tests          532
 # of paths in test names        1

So the whole test run is aborted in the middle.

This patch should fix the issue.

Co-Authored-By: Tom de Vries <tdevries@suse.de>
---
 gdb/testsuite/gdb.base/sigwinch-notty.exp | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

v2: I took over Tom's suggestion 1:1, and gave it a few test runs with
no unexpected test aborts so far.
So this looks quite good to me, and has also a nice improvement of giving
an UNSUPPORTED message, with what exactly was the reason why the test
did not run.

diff --git a/gdb/testsuite/gdb.base/sigwinch-notty.exp b/gdb/testsuite/gdb.base/sigwinch-notty.exp
index cef21c07c59..621231df6af 100644
--- a/gdb/testsuite/gdb.base/sigwinch-notty.exp
+++ b/gdb/testsuite/gdb.base/sigwinch-notty.exp
@@ -19,11 +19,17 @@
 
 require {!target_info exists gdb,nosignals}
 
-# The testfile relies on "run" from the command line, so only works
-# with "target native".
-if { [target_info gdb_protocol] != "" } {
-    return
-}
+# The test-case relies on "run" from the command line, so it only works
+# with "target native", so we need host == target.
+#
+# The test-case uses "exp_pid -i $gdb_spawn_id" which doesn't work with
+# remote host, so we need build == host.
+#
+# In other words, we need build == host == target.
+require {!is_remote host} {!is_remote target}
+
+# Check that we have "target native" as opposed to native-gdbserver etc.
+require {string equal [target_info gdb_protocol] ""}
 
 gdb_exit
 
-- 
2.39.2