Egregious IOsubsystem code excised. Phew, what a relief! Two

Egregious IOsubsystem code excised.  Phew, what a relief!  Two
files (win32/win32io.[ch]) completely removed, as are all traces
of them in makefiles and MANIFEST.  RunPerl() retains the void* arg
for later. Various myfoo() things regularized to my_foo().  CPP not
required anymore to create a perl binary :)

p4raw-id: //depot/win32/perl@242