[P4est] Fix linking to MSMPI when targeting Windows

[giordano]

The old recipe was creating a broken symlink, a better solution is to tell the linker the name of the library to search (and where). Ref: https://github.com/JuliaIO/Tar.jl/pull/165#issuecomment-1880295075.

CC: @JoshuaLampert @sloede