Spellchecking some comments

This PR attempts to clean up some minor spelling mistakes in comments

compiler/rustc_codegen_llvm/src/context.rs

@@ -360,7 +360,7 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
         //   feasible. The compiler may be able to get around this, but it may
         //   involve some invasive changes to deal with this.
         //
-        // The flipside of this situation is that whenever you link to a dll and
+        // The flip side of this situation is that whenever you link to a dll and
         // you import a function from it, the import should be tagged with
         // `dllimport`. At this time, however, the compiler does not emit
         // `dllimport` for any declarations other than constants (where it is

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -1113,7 +1113,7 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
                     && len.try_eval_usize(bx.tcx, ty::ParamEnv::reveal_all())
                         == Some(expected_bytes) =>
             {
-                // Zero-extend iN to the array lengh:
+                // Zero-extend iN to the array length:
                 let ze = bx.zext(i_, bx.type_ix(expected_bytes * 8));
 
                 // Convert the integer to a byte array