nitro-enclaves: mismatched types: NE_SET_USER_MEMORY_REGION expected `i32`, found `u64`

[peppergrayxyz]

Build fails on llvm/musl/libcxx (#429)

Upstream issue: virtee/nitro-enclaves#1
PR has been merged in upstream: virtee/nitro-enclaves#2

   Compiling nitro-enclaves v0.3.0
error[E0308]: mismatched types
    --> /home/pepper/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/nitro-enclaves-0.3.0/src/launch/mod.rs:83:56
     |
83   |             let ret = unsafe { libc::ioctl(self.vm_fd, NE_SET_USER_MEMORY_REGION, r) };
     |                                -----------             ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `u64`
     |                                |
     |                                arguments to this function are incorrect
     |
note: function defined here
    --> /home/pepper/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libc-0.2.172/src/unix/linux_like/linux/mod.rs:7005:12
     |
7005 |     pub fn ioctl(fd: c_int, request: Ioctl, ...) -> c_int;
     |            ^^^^^
help: you can convert a `u64` to an `i32` and panic if the converted value doesn't fit
     |
83   |             let ret = unsafe { libc::ioctl(self.vm_fd, NE_SET_USER_MEMORY_REGION.try_into().unwrap(), r) };
     |                                                                                 ++++++++++++++++++++