elf: add .relr.dyn bootstrap relocation support

[jlinenkohl]

Summary

• Add .relr.dyn bootstrap relocation decoding/application and declaration wiring.

Why

• Modern loaders use RELR; support improves dynamic ELF portability.

Validation

• cd tests && bash run_unit_tests.sh -R test_elf

Depends on

• elf: apply R_X86_64_RELATIVE addend semantics #68

Stack Context

• Follows RELATIVE semantics fix in elf: apply R_X86_64_RELATIVE addend semantics #68.
• Together with linux: fix readlinkat guest copy length handling #67/elf: apply R_X86_64_RELATIVE addend semantics #68, enables clean behavior expected by tests: split elf coverage into no-reloc control and reloc gate #70.

Test Evidence

• Date: 2026-04-02
• Branch-level validation source: phase14_audit baseline sweep
• Full unit harness: cd tests && bash run_unit_tests.sh -> 8/8 passed
• Integration tinytest lane: (cd guest/tests && bash build.sh) && ./build/tinytest guest/tests/glibc_test -> passed

PR-Scoped Command

• cd tests && bash run_unit_tests.sh -R test_elf
• Stacked expectation: evaluate after elf: apply R_X86_64_RELATIVE addend semantics #68 in relocation chain

[fwsGonzo]

This might be a place where we want to fail hard if there is an out-of-bounds address, throwing a MachineException instead of silently ignoring it.

[jlinenkohl]

Thank you for the feedback. That was a miss on my part.

I rebased this branch onto current master and resolved the merge conflict in machine_elf.cpp.

I also addressed the review feedback to fail hard on out-of-bounds RELR writes instead of silently ignoring them:

• single RELR target out of bounds now throws MachineException
• bitmap-derived RELR target out of bounds now throws MachineException

After the rebase + force-push, PR #69 is now mergeable again (GitHub conflict state cleared).

[fwsGonzo]

Thanks!