How was that TC built? koxtoolchain targets glibc-2.15, so it can't pull newer symbols unless you're doing things wrong
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See my earlier mention of disabling hardening, but even if that fixes it, that doesn't mean that your setup isn't seriously broken
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Speaking of: exceedingly few things should require you to manually enforce CC, CXX, AR, NM, LD & friends. Very few things actually rely on a CROSS_something env var either (OTOH, busybox and OpenSSL would be two exceptions, each expecting a slightly different env var, with a slightly different syntax, IIRC).
What *is* almost ubiquitous, though, is autotool's confusingly named --host argument, which accepts a toolchain triplet, and automatically obeys it to set CC & co.
EDIT: As far as 2019.77 is concerned, my best guess is you're picking up your system includes/glibc because of aforementioned mistakes, and as such it's detecting strlcat/strlcpy as available, while they're definitely not
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