it seems to be legitimate to have `mountinfo` lines
to have keywords with spaces such as
```
rootfs overlay / overlay rw,relatime,lowerdir...
```
This was not expected, but for our requirement
we can just ignore this and move forward.
fixes#12047
Signed-off-by: Harshavardhana <harsha@minio.io>
Currently windows support was relying on Symlink as
a way to detect a drive, this doesn't work in latest
Windows 2016, fix this to use a proper mechanism by
using win32 APIs.
Additionally also add support for detecting bind mounts
on Linux.
disk usage crawling is not needed when a tenant
is not sharing the same disk for multiple other
tenants. This PR adds an optimization when we
see a setup uses entire disk, we simply rely on
statvfs() to give us total usage.
This PR also additionally adds low priority
scheduling for usage check routine, such that
other go-routines blocked will be automatically
unblocked and prioritized before usage.
