into '_' to meet sh variable name rules) into a shell string processing
loop.
On my test system, this reduces the total elapsed time for the bin/sh ATF
tests from about 109 secs to about 102 (user cpu from 24.5 to 21, sys cpu
from 34 to 30) and the usr.bin/make tests elapsed time from 42.5 to 40
secs (user from a bit over 15 to a bit over 13, and sys from 16+ to 13+).
(Recorded on an AMD64 domU).
These probably exaggerate the effect, as there are a bunch of quite small
tests, which means the ATF overhead (which this change affects) is a greater
proportion of the total test time than for some other tests where most of
the time is spent actually testing.
But I am fairly confident that there will be at least some improvement.
This could be further improved by removing the cmdsub invocation method,
and instead passing the name of a variable containing the string to
normalise (with the result returned in that same var) - but that would
mean altering all the callers as well. Some other time maybe.