build: use top_builddir instead of relative paths
build: use top_builddir instead of relative paths

The only instance of using a relative path for an internal library is
in tests/Makefile.am. Use top_builddir instead.

Signed-off-by: Anders Roxell <b4e8e89057bc64bc4f9625a4a821c9ac177a7ed2@linaro.org>
Signed-off-by: Bartosz Golaszewski <e5d45fddd9040473413b909b802f629a971ad04c@baylibre.com>

brgl/libgpiod,brgl/libgpiod,brgl/libgpiod,brgl/libgpiod