Remove references to deleted files from Makefiles

After the recent cleanup, couple of references were forgotten in Makefile.am. This made 'make dist' fail.
These files were removed in commits dadec46 and 77ef11a.

PS:
Rainer, does the regular testbench run try to do dist or dist check?
For some reason, I now see some failing tests (queue-persist.sh, imptcp_conndrop-vg.sh) that weren't failing few days ago. Also, make distcheck seems to be broken (not sure if that ever worked). I'll try to look into it later.