tackle various clippy lints

src/header/stdio/constants.rs

@@ -16,7 +16,7 @@ pub const F_SVB: c_int = 64;
 pub const F_APP: c_int = 128;
 pub const F_BADJ: c_int = 256;
 
-/// SEEK_SET, SEEK_CUR and SEEK_END defined in fcntl bits header
+// SEEK_SET, SEEK_CUR and SEEK_END defined in fcntl bits header
 
 pub const _IOFBF: c_int = 0;
 pub const _IOLBF: c_int = 1;

src/header/stdio/printf.rs

@@ -192,11 +192,11 @@ impl VaArg {
         }
 
         let ap_impl = unsafe {
-            let ptr_to_struct = ap as *mut core::ffi::VaList as *mut VaListInner;
+            let ptr_to_struct = core::ptr::from_mut::<core::ffi::VaList>(ap).cast::<VaListInner>();
             &mut *ptr_to_struct
         };
 
-        let ptr = ap_impl.overflow_arg_area as *const c_longdouble;
+        let ptr = ap_impl.overflow_arg_area.cast::<c_longdouble>();
         let val = unsafe { ptr.read() };
 
         ap_impl.overflow_arg_area = unsafe { ap_impl.overflow_arg_area.add(16) };