v850 support for getting main offset

[PeiweiHu]

Your checklist for this pull request

• I've read the guidelines for contributing to this repository
• I made sure to follow the project's coding style
• I've documented or updated the documentation of every function and struct this PR changes. If not so I've explained why.
• I've added tests that prove my fix is effective or that my feature works (if possible)
• I've updated the rizin book with the relevant information (if needed)

Detailed description

Fix #2316. This pr adds support for v850 while getting main offset.

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Test plan

If possible, I hope more v850 samples can be provided for the test (I searched but found only a few).

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Closing issues

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[XVilka]

Please add a testcase.

[wargio]

Can you also add a test? (open a PR on rizin bin repo if needed)

[PeiweiHu]

Explanation for changing test/db/analysis/v850:

I ran aaa; afl on other samples, main is displayed instead of sym.main.

[wargio]

i think we need to test this on a bin without symbols.

[PeiweiHu]

@PeiweiHu could you please rebase and update the PR?

Sorry for the late response. Since this pr is not thoroughly tested, I will refine and reopen this in June (after some of my deadlines) if nobody solves it.

[XVilka]

@PeiweiHu could you please reopen/finish this one again? It would help the ongoing V850 RzIL conversion: #4103

For creating testcases these toolchains could be used:

• https://llvm-gcc-renesas.com/v850/v850-download-toolchains/
• https://github.com/dkulacz/gcc-v850-elf-toolchain
• https://hub.docker.com/r/mikoto2000/v850-toolchain
• https://eclipse-update.iar.com/v850/4.10/

cc @imbillow

[PeiweiHu]

Ok, I will try to finish this when I am free. cc @XVilka

[wargio]

nice