Macos libs - #3948

import_audit.py read ELF and PE only, so it refused every library the
macOS build produces. Mach-O exports live in an export trie rather
than a symbol table, so this walks the trie from LC_DYLD_INFO(_ONLY)
or LC_DYLD_EXPORTS_TRIE, skips weak definitions the way the ELF reader
does, and strips the leading underscore dyld hides and shows again on
lookup.

Running it on PPSA34356 turned up two absent imports, and they turned
out to be __stack_chk_fail and __stack_chk_guard: compiler symbols the
game imports by NID like any other. Adding them to a list kept verbatim
was wrong, because the guest resolves the NID name and nothing
exported it. Letting them be renamed to _f7uOxY9mM1U and _Ou3iL1abvng
fixes the guest side but leaves libkernel.prx holding a reference to a
name libc.prx no longer exports, because PatchChainedImports only
rewrites imports that look guest-facing -- an NID postfix or an sce
prefix, neither of which a compiler symbol has. Widening that filter to
the stack-protector names lets the existing rewrite follow the rename,
so both sides agree and every import in the title resolves.

The export trie reader has tests built around a real trie: a flat root
with one terminal child per name, weak definitions, and the bounds
checks.

The relinker's Mach-O writer gives every relinked image a TLS descriptor
and rewrites each %fs access into a call-out that reads %fs:0, which on
Darwin is pthread_self()->tsd, allocating through
Aps5GuestTlsAllocate when it is null. It also binds
Aps5GuestTlsRegister from the module init stub and
Aps5GuestTlsGetAddr with an addend for a guest that imports
__tls_get_addr. None of the three existed, so any title with a PT_TLS
segment stopped at dyld with "symbol not found in flat namespace".

Aps5GuestTlsAllocate sizes the block from the descriptor, copies the
init image, writes the guest thread pointer into the 16 bytes in front
of the block so a %fs:-16 access reaches it, and publishes the block
through host pthread key 0, which is free because the guest's own
pthread keys are emulated in separate storage. Aps5GuestTlsGetAddr is
the block itself as a thread-local variable, since the relinker binds
its address and adds the guest's offset to it.

The variable needs an asm label: this toolchain emits a Mach-O __thread
variable only outside an extern "C" block, and the default visibility
because the build compiles with -fvisibility=hidden.

Verified against the relinker's own TLS fixture and PPSA34356, both of
which now clear the TLS binds and stop on Aps5StartGuest instead.