Receive multiple file descriptors with a Request

Extending the existing code to support receiving more than one file
descriptor per request. The micro-http crate might be used in a context
where multiple file descriptors are associated with one request, hence
the need to update the micro-http crate.

A concrete example from Cloud Hypervisor is to be able to pass multiple
TAP file descriptors at once when adding a new network interface. This
way it can hotplug a multiqueue device.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

Cargo.lock

@@ -1,5 +1,7 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "bitflags"
 version = "1.2.1"
@@ -22,9 +24,9 @@ dependencies = [
 
 [[package]]
 name = "vmm-sys-util"
-version = "0.8.0"
+version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "01cf11afbc4ebc0d5c7a7748a77d19e2042677fc15faa2f4ccccb27c18a60605"
+checksum = "733537bded03aaa93543f785ae997727b30d1d9f4a03b7861d23290474242e11"
 dependencies = [
  "bitflags",
  "libc",