tests: don't print '\0' character

print "" (which results in no output) instead of
printing '\0' (which is not visible, but is there)

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>
gitignore: adpat to scanner and protocol path changes

Since commit 4c163b9b001bd93aaf97d7e962873a379eb90bfd, wayland-scanner
is built in top builddir instead of src, and protocol files are
generated in protocol subdir instead of src.
Protocol files generated in the new path are already properly ignored
in the toplevel gitignore file.

Signed-off-by: Olivier Blin <olivier.blin@softathome.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
tests: rename NO_ASSERT_LEAK_CHECK

This env variable is used for turning off the leak checks in tests.
Rename it to WAYLAND_TESTS_NO_LEAK_CHECK, so that it is consistent
with WAYLAND_TESTS_NO_TIMEOUTS.

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>
tests: detect if debugger is attached

Copy function from libinput/test/litest.c is_debugger_detached()
and use it in our test-runner. If debugger is attached, turn off
leak checks and timeouts automatically.

Revision of libinput: 028513a0a723e97941c39c4aeb17433198723913

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>