Implement Unix pid maps for `winedbg`

[marzent]

This patch adds a new info command processmap to winedbg, which produces the following output:

Wine-dbg>info procmap
 pid      unix_pid threads  executable (all id:s are in hex)
 0000004c 0000772d 3        'explorer.exe'
 00000038 00007729 7        'services.exe'
 000000d8 0000773b 6        \_ 'rpcss.exe'
 000000b8 00007737 3        \_ 'svchost.exe'
 000000a0 00007732 4        \_ 'plugplay.exe'
 0000006c 0000772f 7        \_ 'winedevice.exe'
 00000044 0000772b 6        \_ 'winedevice.exe'
 00000020 0000771e 1        'start.exe'
 00000128 0000775e 2        \_ 'conhost.exe'