bugs in cforth

[M. Cain]

   Found a couple of small things while getting the code
up and running on our Pyramid:

 - Getblocks() wasn't recognizing the existance of
   forth.block because fopen(blockfile,"a+") didn't
   leave the pointer at the end of the file.  Fixed
   it by inserting an fseek(blockfile,0L,2) after
   the open.  This is definitely a Pyramid problem,
   but I couldn't recreate it in my own tests.

 - In prslw(), unwrittenflag is not initialized.
   Where memory is initially filled with zeroes
   before loading, no problems.  Doesn't appear to
   be the case on the Pyramid.  Fixed by initializing
   to !TRUE.

Other than that, things came up very easily, and it all
seems to work fine.

Michael Cain
Bell Communications Research