Fix incorrect continue condition in PreopeonList
Fix incorrect continue condition in PreopeonList

Also, check for overflow on incremented file descriptors. Previously,
we'd trigger a panic if we exceeded the `fd_t` resolution. Now, instead,
we throw an `error.Overflow` to signal that there can be no more
file descriptors available from the runtime. This way we give the user
the ability to still be able to check if their desired preopen exists
in the list or not.

raulgrell/zig,raulgrell/zig,zig-lang/zig,zig-lang/zig,raulgrell/zig,raulgrell/zig,zig-lang/zig,andrewrk/zig,raulgrell/zig,andrewrk/zig