build(deps): bump signal-hook from 0.2.2 to 0.3.2

Manually changed to reflect changes in mutability of signals and
rearrangement of constants.

Bumps [signal-hook](https://github.com/vorner/signal-hook) from 0.2.2 to 0.3.2.
- [Release notes](https://github.com/vorner/signal-hook/releases)
- [Changelog](https://github.com/vorner/signal-hook/blob/master/CHANGELOG.md)
- [Commits](https://github.com/vorner/signal-hook/compare/v0.2.2...v0.3.2)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
Signed-off-by: Rob Bradford <robert.bradford@intel.com>

vmm/Cargo.toml

@@ -36,7 +36,7 @@ seccomp = { git = "https://github.com/firecracker-microvm/firecracker", tag = "v
 serde = {version = ">=1.0.27", features = ["rc"] }
 serde_derive = ">=1.0.27"
 serde_json = ">=1.0.9"
-signal-hook = "0.2.2"
+signal-hook = "0.3.2"
 tempfile = "3.1.0"
 thiserror = "1.0"
 url = "2.2.0"

vmm/src/vm.rs

@@ -51,7 +51,11 @@ use linux_loader::loader::elf::Error::InvalidElfMagicNumber;
 use linux_loader::loader::elf::PvhBootCapability::PvhEntryPresent;
 use linux_loader::loader::KernelLoader;
 use seccomp::{SeccompAction, SeccompFilter};
-use signal_hook::{iterator::backend::Handle, iterator::Signals, SIGINT, SIGTERM, SIGWINCH};
+use signal_hook::{
+    consts::{SIGINT, SIGTERM, SIGWINCH},
+    iterator::backend::Handle,
+    iterator::Signals,
+};
 use std::cmp;
 use std::collections::{BTreeMap, HashMap};
 use std::convert::TryInto;
@@ -1433,7 +1437,7 @@ impl Vm {
     }
 
     fn os_signal_handler(
-        signals: Signals,
+        mut signals: Signals,
         console_input_clone: Arc<Console>,
         on_tty: bool,
         exit_evt: EventFd,