test/xmod/collide_test.ww replaces 989_fnptrcollide_run.c and
989_barefn_collide_run.c with every assertion preserved (build-reject
both stages; run-exit 9 + exactly-one TEXT main.run/aa.run + cs==ww).
Makefile grows the XMOD_WW_TESTS block mirroring SEP_WW_TESTS, wired
into test-compiler.
