Fix some clippy warnings.

lib/execute/src/signalhandlers.rs

@@ -45,7 +45,7 @@ pub fn ensure_eager_signal_handlers() {
     }
 
     state.tried = true;
-    assert!(state.success == false);
+    assert!(!state.success);
 
     if !unsafe { EnsureEagerSignalHandlers() } {
         return;
@@ -64,7 +64,7 @@ fn ensure_darwin_mach_ports() {
     }
 
     state.tried = true;
-    assert!(state.success == false);
+    assert!(!state.success);
 
     if !unsafe { EnsureDarwinMachPorts() } {
         return;

lib/execute/src/traphandlers.rs

@@ -54,7 +54,7 @@ pub extern "C" fn Unwind() {
 #[no_mangle]
 pub extern "C" fn LookupCodeSegment(_pc: *const ::std::os::raw::c_void) -> *const CodeSegment {
     // TODO: Implement this.
-    unsafe { mem::transmute(-1isize) }
+    -1isize as *const CodeSegment
 }
 
 /// A simple guard to ensure that `JMP_BUFS` is reset when we're done.