Prevent missing lsb_release from stopping setup

[sicada]

When trying to run the installation script bin/setup_daq, it is possible to run into an error like:

user@host:~/code/faucetsdn-daq$ ./bin/setup_daq
Linux host 4.4.0-19041-Microsoft #488-Microsoft Mon Sep 01 13:43:00 PST 2020 x86_64 GNU/Linux
./bin/setup_daq: line 4: lsb_release: command not found

This occurs when the linux package lsb-core is not installed, since it's not guaranteed to be installed by default on all distributions. For example, debian running in the Windows Subsystem for Linux did not have it installed by default.

It appears that lsb-core ends up being installed later in the setup_daq process anyway, so this PR proposes that we just check for lsb_release and emit a warning if it isn't yet installed. This will prevent the setup script from exiting with an error that may be cryptic to some people.

[sicada]

Thanks @grafnu, I updated the PR to address your comments.

[codecov[bot]]

Codecov Report

Merging #903 (cecdaf1) into master (04cb182) will decrease coverage by 0.01%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #903      +/-   ##
==========================================
- Coverage   82.21%   82.19%   -0.02%     
==========================================
  Files          45       45              
  Lines        5556     5556              
==========================================
- Hits         4568     4567       -1     
- Misses        988      989       +1     

Flag	Coverage Δ
ata	62.93% <ø> (ø)
aux	68.42% <ø> (-0.02%)	:arrow_down:
base	66.37% <ø> (-0.06%)	:arrow_down:
dhcp	67.67% <ø> (ø)
many	67.64% <ø> (+0.07%)	:arrow_up:
mud	72.59% <ø> (+0.03%)	:arrow_up:
switch	67.65% <ø> (-0.04%)	:arrow_down:
topo	66.68% <ø> (ø)
unit	31.82% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
daq/acl_state_collector.py	82.19% <0.00%> (-1.37%)	:arrow_down:
daq/runner.py	84.74% <0.00%> (-0.22%)	:arrow_down:
daq/topology.py	97.15% <0.00%> (-0.17%)	:arrow_down:
daq/host.py	90.98% <0.00%> (-0.15%)	:arrow_down:
daq/traffic_analyzer.py	89.68% <0.00%> (+3.17%)	:arrow_up:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 04cb182...cecdaf1. Read the comment docs.