Move a function added to test-lib-functions.sh in ea047a8eb4f (t5310:
factor out bitmap traversal comparison, 2020-02-14) into a new
lib-bitmap.sh.
The test-lib-functions.sh file should be for functions that are widely
used across the test suite, if something's only used by a few tests it
makes more sense to have it in a lib-*.sh file.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
