Fixed how the *.tar.bz2 are formed. The calc-2.12.8.0.tar.bz2 file
that was formed for calc version 2.12.8.0 was missing most files.
Expanded 'make chk' to also verify that 'make distchk' and 'make
distlist' execute successfully. This will help check a regression
of the bug that produced the bogus calc-2.12.8.0.tar.bz2 file.
Added additional regression tests related 0^(zero_expression)==1.
8af0b351ae