Remove caching from getlogin(2).

[brooks]

Summary

This caching has existed since the CSRG import, but serves no obvious
purpose. Sure, setlogin() is called rarely, but calls to getlogin()
should also be infrequent. The required invalidation was not
implemented on aarch64, arm, mips, amd riscv so updates would never
occur if getlogin() was called before setlogin().

Reported by: Ali Mashtizadeh <[e-mail]>

Test Plan

needs a universe build

[kib]

lib/libc/gen/getlogin.c

77

Why is this strncpy() ?

[brooks]

Prefer strlcpy().

No functional change as the old code checked and checked and limited
length.

[emaste]

Makefile.inc1

805

It's not converted *to* a MD assembly stub though?

807

Aside, it's probably time to retire this one (ptrace), I'll take care of that later.

[brooks]

• rebase
• Remove -DNO_CLEAN changes to Makefile.inc1. They will be in a seperate commit.