oakcodec: gate find_ffmpeg_searches_path to unix (chmod 0755 + shebang
fixture) and make find_ffmpeg_missing_returns_empty assert absoluteness
instead of a '/' prefix so the tests compile and pass on Windows.
ci (Windows): export RUSTFLAGS=-C link-args=-lmsvcrt in the build and
test steps. mingw-w64 (Nov 2025) forwards _assert to __msvcrt_assert
inside libmingwex.a, and rustc's link order leaves -lmingwex last, so
binaries that pull _assert.o (oakcommon's real_ocio test) fail to link;
a trailing -lmsvcrt re-scans the CRT import lib afterwards.
ci (Linux): copier_test dies inside ld.so before printing anything.
Replace the LD_DEBUG probe with stronger forensics: exported dynsyms
(interposition suspects), strace tail, valgrind tail, and siginfo
(si_code/si_addr) from the gdb run.
Mike-Solar
8660cbcf97