[Fuzzer] Update _zx_port_wait function use in Fuchsia port

Fuchsia's _zx_port_wait no longer takes the count argument. This
change also updates all symbol uses to use the underscored versions.

Differential Revision: https://reviews.llvm.org/D47403

llvm-svn: 333328
GitOrigin-RevId: 796bb7d4ceb520bf611ead899ba56324761edaa8
1 file changed