[CVS ci] build imcc as parrot - 4: cleanup Test.pm; allow PIR tests in main

[Leopold Toetsch]

I've committed that part directly as it should be totally independent of 
the immanent changes to the build system.

It cleans up some remaining cruft from the old days when assemble.pl 
happened to be used.

More importantly there are now two different ways to run tests through 
the PIR assembler:

From t/op/basic.t:

output_is(<<'CODE', <<'OUTPUT', "pir syntax with marker - is");
##PIR##
.sub _main
     .const string OK = "ok\n"
     print OK
     end
.end
pir_output_is(<<'CODE', <<'OUTPUT', "pir syntax with function - is");
.sub _main
     .const string OK = "ok\n"
     print OK
     end
.end
"make clean" changes will be done with root.in.

leo