Building a tool against libfst: GTKWave 3.3.x's bundled fstapi is too old for newer reader APIs

Compiling a tool that reads FST with fstReaderIterBlocks2 / newer fstReader* calls against the fstapi.c/fstapi.h bundled in GTKWave 3.3.116's source tree (src/helpers/fst) fails with undeclared-identifier errors (e.g. the reader context never gets declared because a newer call doesn't exist). Use the standalone libfst repo (github.com/gtkwave/libfst) at a pinned commit instead: compile fstapi.c, lz4.c, fastlz.c with -O2 and link with -lz (plus whatever your tool needs, e.g. -lzstd -lcrypto). Files written by GTKWave 3.3.116's vcd2fst read fine with the newer library. Pin the commit in your build script so results are reproducible.