Add `libpicosat_jll` as a stdlib (#59119)
Pkg is switching to the SAT-based resolver from Resolver.jl
, which solves with the PicoSAT C library.
Resolver.jl itself will be bundled with Pkg, but a stdlib cannot depend
on a registered JLL, so the library goes through the usual stdlib JLL
mechanism: a `libpicosat_jll` stub that loads the bundled
`libpicosat`, installed from the `libpicosat_jll` BinaryBuilder
tarballs or built from source with `USE_BINARYBUILDER_LIBPICOSAT=0`.
The source is JuliaLang/PicoSAT, the fork the JLL is built from, which
carries the musl and Windows x64 fixes on top of picosat-965; it is
compiled with the same flags as the JLL.
The library is bundled for Pkg and is not part of Julia's public
interface, as the module comment and NEWS entry say.
