The chain is the part of this package set that cannot be read off any one
file: four compilers, each a step further along, and two `libgcc`s either
side of the libc. Until now it was only recoverable by reading the
`overrideCC` call sites in order and reconstructing the argument.
Write it down once, as a table, next to why the cycle needs breaking at
all -- a libc's sources call into libgcc, and a libgcc that can use the
libc's threads needs the libc. Also record the two things that are easy
to get wrong and hard to notice: that the pre-libc stage is written down
in exactly one place (`binutilsNoLibc` carrying `preLibcHeaders` as its
`libc`), and that a libgcc built with `inhibit_libc` still compiles,
links and installs, just with pieces silently missing.
The per-wrapper comments shrink to what is local to each -- which stage it
is and what keeps the libc out -- since the chain-wide narrative now has
somewhere better to live.
Assisted-by: Claude Code (Claude Opus 5)
