added blosc recipe

[pepijn-devries]

With this addition, webr is building without problems. I'm not 100% the added recipe is correct. Please let me know if there is anything I can do to facilitate

[georgestagg]

Sorry for the slow reply. I tried this locally but get,

emconfigure: error: '../configure --enable-shared=no --enable-static=yes --with-zstd --with-zlib --with-lz4 --prefix=/Users/georgestagg/work/webr/wasm' failed: [Errno 2] No such file or directory: '../configure'

Possibly the blosc project builds using cmake or some other alternative build system.

In #593 I have added extra workflows to test this better in CI. Once that has merged, basing your branch on main should run the extra checks when adding new library recipes like this.

[pepijn-devries]

Thanks, I will try to fix this in my fork, and test with the new CI.