Patch every `derivation` call in the bootsrap process to add it a
conditional `__contentAddressed` parameter.
That way, passing `contentAddressedByDefault` means that the entire
build closure of a system can be content addressed
The linker scripts no longer contain store paths, so this does nothing. More
importantly, libpthread.so is not longer a linker script on ARM, so the patching
would corrupt it.
On one hand, don't want to pass garbage that affects hash, on the other
hand footguns are bad.
Now, factored out the derivation so only need to pass in what is used.
