Decode arguments to dup, dup2, getdirentries, pread, and pwrite.

• dup and dup2 print fd arguments in decimal.
• pread and pwrite are similar to read and write with the addition of the file offset.
• getdirentries displays the output entries as a string for now and also prints the value returned in *basep. Eventually the buffer for getdirentries should perhaps be decoded as an array of dirent structures.

PR: 214885
Submitted by: Jonathan de Boyne Pollard <J.deBoynePollard-newsgroups@NTLWorld.COM>