[Backport release-24.05] doc/stdenv: hardening flags: update, add sections on `fortify3`, `zerocallusedregs`, `trivialautovarinit` #318270

Evaluator Performance Report

stat	before	after	Δ	Δ%
cpuTime	653.11	657.28	↗ 4.18	0.64%
envs-bytes	20,976,455,200	20,976,455,200	0
envs-elements	1,104,588,044	1,104,588,044	0
envs-number	758,734,428	758,734,428	0
gc-heapSize	58,976,079,872	59,143,852,032	↗ 167,772,160	0.28%
gc-totalBytes	130,057,544,688	130,057,528,560	↘ 16,128	-0.00%
list-bytes	3,660,198,024	3,660,198,024	0
list-concats	83,772,433	83,772,433	0
list-elements	457,524,753	457,524,753	0
nrAvoided	879,250,182	879,250,182	0
nrFunctionCalls	697,519,685	697,519,685	0
nrLookups	364,586,348	364,586,348	0
nrOpUpdateValuesCopied	1,896,427,921	1,896,427,921	0
nrOpUpdates	86,112,692	86,112,692	0
nrPrimOpCalls	363,860,014	363,860,014	0
nrThunks	1,081,723,278	1,081,723,278	0
sets-bytes	43,008,032,304	43,008,032,304	0
sets-elements	2,526,220,516	2,526,220,516	0
sets-number	161,781,503	161,781,503	0
sizes-Attr	16	16	0
sizes-Bindings	16	16	0
sizes-Env	16	16	0
sizes-Value	24	24	0
symbols-bytes	2,465,243	2,465,243	0
symbols-number	172,128	172,128	0
values-bytes	33,352,070,256	33,352,070,256	0
values-number	1,389,669,594	1,389,669,594	0