Fix typo

Co-Authored-By: Mazdak Farrokhzad <twingoow@gmail.com>

src/libcore/alloc.rs

@@ -225,7 +225,7 @@ impl Layout {
         // > `usize::MAX`)
         let new_size = self.size() + pad;
 
-        // SAFETY: This necessarily respectes the from_size_align
+        // SAFETY: This necessarily respects the from_size_align
         // prerequisites per the above.
         unsafe { Layout::from_size_align_unchecked(new_size, self.align()) }
     }