fix(location&context): Fix clippy errors

Author: tempdragon

src/context.rs

@@ -1215,7 +1215,6 @@ pub unsafe fn from_ptr<'ctx>(ptr: *mut gccjit_sys::gcc_jit_context) -> Context<'
 #[cfg(test)]
 mod tests {
     use super::super::*;
-    use std::default::Default;
     use std::mem;
 
     #[test]

src/location.rs

@@ -27,10 +27,10 @@ impl<'ctx> fmt::Debug for Location<'ctx> {
 }
 
 impl<'ctx> Location<'ctx> {
-    pub fn null<'a>() -> Self {
+    pub fn null() -> Self {
         Location {
             marker: std::marker::PhantomData,
-            ptr: unsafe { core::ptr::null_mut() },
+            ptr: core::ptr::null_mut(),
         }
     }
 }