fix up faulty perl embeddings

fix up faulty perl embeddings

Some platform-specific embeddings of perl were misusing the
return values from perl_parse() and perl_run(), in some cases
causing failure due to exit(0) combined with the recent changes
in commit 0301e899536a22752f40481d8a1d141b7a7dda82.  Commit
d4a50999a5525c2681d59cae5fcd94f94ff897fd partially fixed a Windows
embedding.  More fully fix that, along with NetWare and OS/2.  Even in
embeddings with correct logic, stop using a variable named "exitstatus"
to hold the result of perl_parse() or perl_run(), to avoid misleading
people who copy the code.