This patch adds general infrastructure to RDMAtool to handle various
filtering options needed for the downstream resource tracking patches.
The infrastructure is generic and stores filters in list of key<->value
entries. There are three types of filters:
1. Numeric - the values are intended to be digits combined with '-' to
mark range and ',' to mark multiple entries, e.g. pid 1-100,234,400-401
is perfectly legit filter to limit process ids.
2. String - the values are consist from strings and "," as a denominator.
3. Link - special case to allow '/' in string to provide link name, e.g.
link mlx4_1/2.
Signed-off-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>