when exe have strip unw_get_proc_name get the function name is wrong

[chall1123]

Environment

• libunwind version:
• architecture:
• OS:X86

Description
A clear and concise description of what the bug is.

i define a static function ,and the exe is stripped, unw_get_proc_name get the function name is wrong, if cannot get the name, unw_get_proc_name should is return error or the name is null

Reproduction Steps
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