doc/stdenv: hardening flags: update, add sections on `fortify3`, `zerocallusedregs`, `trivialautovarinit` #317575

Evaluator Performance Report

stat	before	after	Δ	Δ%
cpuTime	658.73	659.06	↗ 0.33	0.05%
envs-bytes	21,067,878,776	21,067,878,776	0
envs-elements	1,109,290,935	1,109,290,935	0
envs-number	762,096,956	762,096,956	0
gc-heapSize	59,210,960,896	59,210,960,896	0
gc-totalBytes	130,366,028,144	130,366,023,840	↘ 4,304	-0.00%
list-bytes	3,673,665,776	3,673,665,776	0
list-concats	84,268,188	84,268,188	0
list-elements	459,208,222	459,208,222	0
nrAvoided	883,990,750	883,990,750	0
nrFunctionCalls	700,638,817	700,638,817	0
nrLookups	366,165,938	366,165,938	0
nrOpUpdateValuesCopied	1,896,336,517	1,896,336,517	0
nrOpUpdates	86,475,041	86,475,041	0
nrPrimOpCalls	365,988,284	365,988,284	0
nrThunks	1,086,571,611	1,086,571,611	0
sets-bytes	43,033,122,592	43,033,122,592	0
sets-elements	2,527,116,365	2,527,116,365	0
sets-number	162,453,797	162,453,797	0
sizes-Attr	16	16	0
sizes-Bindings	16	16	0
sizes-Env	16	16	0
sizes-Value	24	24	0
symbols-bytes	2,473,604	2,473,604	0
symbols-number	172,612	172,612	0
values-bytes	33,449,488,464	33,449,488,464	0
values-number	1,393,728,686	1,393,728,686	0