Replace parking_lot with std::sync types

As of rust-lang/rust#95035, the locking API
provided by std::sync is improved on Linux, outperforming parking_lot in
various cases. Using the built-in locking APIs means we can remove
parking_lot as a dependency, along with its own (indirect) dependencies;
removing a total of 10 dependencies.

vm/Cargo.toml

@@ -14,7 +14,6 @@ libffi-system = ["libffi/system"]
 
 [dependencies]
 num_cpus = "^1.13"
-parking_lot = "^0.12"
 
 # Newer versions of the `time` crate only expose local time behind a
 # compile-time --cfg flag. This isn't viable for us, as it makes the compilation

vm/src/permanent_space.rs

@@ -7,9 +7,9 @@ use crate::mem::{
 };
 use crate::process::Future;
 use ahash::AHashMap;
-use parking_lot::Mutex;
 use std::mem::size_of;
 use std::ops::Drop;
+use std::sync::Mutex;
 
 pub(crate) const INT_CLASS: usize = 0;
 pub(crate) const FLOAT_CLASS: usize = 1;
@@ -169,7 +169,7 @@ impl PermanentSpace {
     /// If an Inko String has already been allocated for the given Rust String,
     /// the existing Inko String is returned; otherwise a new one is created.
     pub(crate) fn allocate_string(&self, string: String) -> Pointer {
-        let mut strings = self.interned_strings.lock();
+        let mut strings = self.interned_strings.lock().unwrap();
 
         if let Some(ptr) = strings.get(&string) {
             return *ptr;
@@ -190,15 +190,15 @@ impl PermanentSpace {
         } else {
             let ptr = ptr.as_permanent();
 
-            self.permanent_objects.lock().push(ptr);
+            self.permanent_objects.lock().unwrap().push(ptr);
             ptr
         }
     }
 
     pub(crate) fn allocate_float(&self, value: f64) -> Pointer {
         let ptr = Float::alloc(self.float_class(), value).as_permanent();
 
-        self.permanent_objects.lock().push(ptr);
+        self.permanent_objects.lock().unwrap().push(ptr);
         ptr
     }
 
@@ -290,11 +290,11 @@ impl PermanentSpace {
 impl Drop for PermanentSpace {
     fn drop(&mut self) {
         unsafe {
-            for pointer in self.interned_strings.lock().values() {
+            for pointer in self.interned_strings.lock().unwrap().values() {
                 InkoString::drop_and_deallocate(*pointer);
             }
 
-            for ptr in self.permanent_objects.lock().iter() {
+            for ptr in self.permanent_objects.lock().unwrap().iter() {
                 ptr.free();
             }