git-daemon: use test_atexit in the tests

This makes use of the just-introduced consistent way to specify that a
long-running process needs to be terminated at the end of a test script
run.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

t/interop/i5500-git-daemon.sh

@@ -37,5 +37,4 @@ test_expect_success "fetch with $VERSION_B" '
 	test_cmp expect actual
 '
 
-stop_git_daemon
 test_done

t/lib-git-daemon.sh

@@ -13,7 +13,6 @@
 #
 #	test_expect_success ...
 #
-#	stop_git_daemon
 #	test_done
 
 test_tristate GIT_TEST_GIT_DAEMON
@@ -43,7 +42,7 @@ start_git_daemon() {
 
 	mkdir -p "$GIT_DAEMON_DOCUMENT_ROOT_PATH"
 
-	trap 'code=$?; stop_git_daemon; (exit $code); die' EXIT
+	test_atexit 'stop_git_daemon'
 
 	say >&3 "Starting git daemon ..."
 	mkfifo git_daemon_output

t/t5570-git-daemon.sh

@@ -211,5 +211,4 @@ test_expect_success FAKENC 'hostname interpolation works after LF-stripping' '
 	test_cmp expect actual
 '
 
-stop_git_daemon
 test_done