bcc/tools: use device number and inode number to identify a file

bcc/tools: use device number and inode number to identify a file

Currently, the filetop tool use (tid, filename, type) tuple to
key a file, which is not enough to uniquely identify a file.
A thread write to multi files with the same name would add up to
same value in the map which can be repro by the following command:

$ cat somefile | tee /foo/bar/xxx /fuz/baz/xxx

Let us add device number and inode number to uniquely identify
a file.

Signed-off-by: Hengqi Chen <chenhengqi@outlook.com>