Unfortunately some duplicate files must remain in lib/libc/wasi/libc-top-half
because they include internal headers *in the same directory* which have edits
relative to upstream musl. Because C is an amazing language, there is no way to
make it so that e.g. upstream musl's src/stdio/fputc.c includes wasi-libc's
src/stdio/putc.h instead of the upstream putc.h. The preprocessor always
searches the current directory first for quote includes.
Anyway, this still takes us from 2.9M to 1.4M for the combination of
lib/libc/wasi and lib/libc/include/wasm-wasi-musl, so I still call it a win.
Also remove all the wasi-libc files we used to ship, but never compile.
The latest wasi-libc HEAD has an extra commit (a6f871343313220b76009827ed0153586361c0d5), which makes preopen initialization lazy.
Unfortunately, that breaks quite a lot of things on our end. Applications now need to explicitly call __wasilibc_populate_preopens() everywhere when the libc is linked. That can wait after 0.11.
* Update wasi-libc to a00bf321eeeca836ee2a0d2d25aeb8524107b8cc
It includes a port of emscripten's allocator that performs
performs much better than the old one.
Most importantly, it includes the prerequisites to later add
support for POSIX threads.
