[Fuzzer] Update the header path for fdio/spawn.h on Fuchsia

The path now includes lib/ prefix.

Differential Revision: https://reviews.llvm.org/D47866

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@334213 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed