fix, PEBKAC, compare with same signedness in xcmp() and xicmp()

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
hygiene, constify where possible

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
hygiene, subtract compatible pointers in return value code of xcmp() and xicmp()

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
test, provide regressions for signedness bug in wu-manber

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'core/glep'

* core/glep:
  test, provide regressions for signedness bug in wu-manber
  hygiene, subtract compatible pointers in return value code of xcmp() and xicmp()
  hygiene, constify where possible
  fix, PEBKAC, compare with same signedness in xcmp() and xicmp()