Fix warning in alloc_system.rs

Author: bjorn3

example/alloc_system.rs

@@ -80,7 +80,6 @@ mod platform {
     extern "system" {
         fn GetProcessHeap() -> HANDLE;
         fn HeapAlloc(hHeap: HANDLE, dwFlags: DWORD, dwBytes: SIZE_T) -> LPVOID;
-        fn HeapReAlloc(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID, dwBytes: SIZE_T) -> LPVOID;
         fn HeapFree(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID) -> BOOL;
         fn GetLastError() -> DWORD;
     }
@@ -111,7 +110,7 @@ mod platform {
             allocate_with_flags(layout, HEAP_ZERO_MEMORY)
         }
         #[inline]
-        unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+        unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
             let header = get_header(ptr);
             let err = HeapFree(GetProcessHeap(), 0, header.0 as LPVOID);
             debug_assert!(err != 0, "Failed to free heap memory: {}", GetLastError());