5962522fbc depends: bump native_cctools for fixed lto with external clang (Cory Fields)
00d1ba7aaa depends: enable lto support for Apple's ld64 (Cory Fields)
Pull request description:
This didn't work for a few reasons (various toolchain compatibility issues) the last time I tested it, but after the last round of bumps it works with no apparent issues.
Note that this does not _enable_ LTO by default in any way, only hooks up the machinery for ```-flto``` to work correctly when specified.
Lines were split for an easier rebase after #17919 is merged.
ACKs for top commit:
fanquake:
ACK 5962522fbc. The relevant option upstream is [here](https://github.com/tpoechtrager/cctools-port/blob/master/cctools/m4/llvm.m4#L4).
Tree-SHA512: df2775e74e7bc847e6cef94cb8457d503d6c9e2fdea861e51386fa6ed5a7ba688241db3685561ae1a32f66724c1b3801727252025f00c04b90a3bdc8a4f6f93b
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