build-sys: Enable testing of sigqueue

The referenced commits enavled both pkill and kill to send an integer to
the killed or signalled process. The test_process now will report on the
integer if sent and the testsuite changes take advantage of this
new feature.

Another process make/destroy set had to be made as using spawn
instead of exec changes both the SID and TTY for the underlying
process, making other tests fail.

References:
 commit 7d55409b82
 commit 2b804a532a

testsuite/pkill.test/pkill.exp

@@ -18,7 +18,6 @@ expect_pass "$test" "^\(lt-\)\?pkill: no matching criteria specified\\s*"
 make_testproc
 set testproc_len [ string length $testproc_comm ]
 set testproc_trim [ string range $testproc_comm 0 [ expr { $testproc_len - 2 } ] ]
-set testproc1_sid [ exec $ps --no-headers -o sid $testproc1_pid ]
 
 set test "pkill find both test pids"
 spawn $pkill -0 -e $testproc_comm
@@ -34,3 +33,19 @@ expect_pass "$test" "invalid option -- '0'"
 
 # Cleanup
 kill_testproc
+
+make_pipeproc
+
+set test "pkill with SIGUSR1"
+spawn $pkill -USR1 -e $testproc_comm
+expect_pipeproc_pass "$test" "SIG SIGUSR1"
+
+set test "pkill with SIGUSR2"
+spawn $pkill -USR2 -e $testproc_comm
+expect_pipeproc_pass "$test" "SIG SIGUSR2"
+
+set test "pkill with queued int"
+spawn $pkill -USR1 -e -q 42 $testproc_comm
+expect_pipeproc_pass "$test" "SIG SIGUSR1 value=42"
+
+kill_pipeproc