elf_parser: clamp overlapping function boundaries from external sources

[jlsandri]

Problem

When function boundaries come from an external source (e.g. a Ghidra auto-analysis export), the reported ranges can overlap: a parent function's length is reported as including its nested sub-functions. A concrete example seen in the wild is a 52-byte function reported as 456 bytes because Ghidra's auto-analysis folded nested sub_xxx children into the parent's size.

When the recompiler imports these, extractFunctions() happily keeps both the oversized parent and the nested children. The parent then gets code-generated with all the sub-function bodies inlined, and the per-call PC-mismatch safety checks inside the inlined sub-calls cascade early-returns up the entire call chain at runtime.

Fix

After merging all function sources in extractFunctions(), walk the sorted function list and clamp each function's end to the start of the next function. An exemption is carved out when the gap is < 16 bytes so that the legitimate "entry-slice" pattern (multiple entry points into a single logical function, spaced a few instructions apart) is preserved.

Scope

• One file touched: ps2xRecomp/src/lib/elf_parser.cpp
• +21 / -0
• No behavioural change for well-formed function maps — the clamp only fires when the imported data is actually inconsistent.

Rationale

This is purely defensive. The recompiler already expects non-overlapping function ranges; this commit enforces that invariant at import time instead of letting the downstream codegen produce wrong output silently.

[jlsandri]

Closing as part of a batch cleanup after #107 landed. The runtime ecosystem refactor in #107 substantially reworked the files this PR touched, and I would like to re-audit the underlying fix against the new code structure before putting it back in front of you. If the fix is still needed after that re-audit, I will re-open as a focused PR rebased onto current main. Thanks for your patience.