PPSA28997 (IL2CPP) calls sceLibcBacktraceGetBufferSize and
sceLibcBacktraceSelf. On Linux the host call stack is captured with
backtrace and each frame is resolved to its module and offset with
dladdr, then written as a linked list of frame records. The record
layout is inferred and listed in TechnicalDebt. Windows throws.
Add missing libc.prx symbols required by Unity IL2CPP runtime:
- Implement _Dtest double classification in Math.cpp
- Implement _Inf double constant in Math.cpp
- Implement sceLibcBacktraceGetBufferSize and sceLibcBacktraceSelf in Backtrace.cpp
- Implement _Cnd_signal in Threads.cpp
- Implement _ZNSt8ios_base7_AddstdEPS_ in RuntimeSupport.cpp
- Implement __pointer_type_info and __function_type_info vtables in TypeInfo.cpp
- Remove duplicate stubs from libSceAmpr/Export.cpp
- Add unit tests in GuestMath.cpp and GuestLibcThreads.cpp
- Document unverified behaviors in docs/dev/debt/libc.md