Check for __unw_add_dynamic_eh_frame_section in non-ORC-runtime exception registration paths.

[lhames]

Background:

LLVM JIT clients using libunwind on Linux have historically encountered "FDE is really a CIE" errors and associated issues with exception handling (see e.g. #86).

To address these issues @housel added new dynamic registration functions for eh-frame-sections to libunwind in bab3981 (__unw_add_dynamic_eh_frame_section registers a section, __unw_remove_dynamic_eh_frame_section deregisters it), and updated the ORC runtime was updated to check for and use these registration functions in 981523b.

@housel's patch fixes the issue for JIT clients who use the ORC runtime, but the LLVM-only registration paths are still hardcoded to use the __register_frame and __deregister_frame functions. We should update the LLVM-only paths to check and use these functions too.

[llvmbot]

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