win32: fix ssh://host:port when using Plink
Moves ssh argument building to platform specific utils code.
The win32 version looks for plink in ssh command string and
uses '-P' in lieu of '-p' for specifying a port
adding foo
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
adding foo
rev offset length base linkrev nodeid p1 p2
0 0 0 0 0 b80de5d13875 000000000000 000000000000
1 0 24 0 1 0376abec49b8 000000000000 000000000000