tests: Call test_cleanup in backtrace-subr.sh check_unsupported.

We want to make sure all (temporary) test files are cleaned up even when
we exit 77 to skip the testcase.

https://sourceware.org/bugzilla/show_bug.cgi?id=23901

Tested-by: Kurt Roeckx <kurt@roeckx.be>
Signed-off-by: Mark Wielaard <mark@klomp.org>

tests/ChangeLog

@@ -1,3 +1,8 @@
+2018-11-21  Mark Wielaard  <mark@klomp.org>
+
+	* backtrace-subr.sh (check_unsupported): Call test_cleanup before
+	exit.
+
 2018-11-17  Mark Wielaard  <mark@klomp.org>
 
 	* run-strip-version.sh: New test.

tests/backtrace-subr.sh

@@ -85,6 +85,7 @@ check_unsupported()
   testname=$2
   if grep -q ': Unwinding not supported for this architecture$' $err; then
     echo >&2 $testname: arch not supported
+    test_cleanup
     exit 77
   fi
 }