Rename align to platform_align on Scalar and Primitive

To emphasize that just because you see a `Scalar(I32)` that doesn't really tell you anything about the alignment it has -- one should be looking at the type (well, the place) for that.

No actual layout or behaviour changes in *this* PR.

Author: scottmcm

src/builder.rs

@@ -1064,7 +1064,7 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
                 },
             )
         } else if let abi::BackendRepr::ScalarPair(ref a, ref b) = place.layout.backend_repr {
-            let b_offset = a.size(self).align_to(b.align(self).abi);
+            let b_offset = a.size(self).align_to(b.default_align(self).abi);
 
             let mut load = |i, scalar: &abi::Scalar, align| {
                 let ptr = if i == 0 {

src/type_of.rs

@@ -325,7 +325,8 @@ impl<'tcx> LayoutGccExt<'tcx> for TyAndLayout<'tcx> {
             return cx.type_i1();
         }
 
-        let offset = if index == 0 { Size::ZERO } else { a.size(cx).align_to(b.align(cx).abi) };
+        let offset =
+            if index == 0 { Size::ZERO } else { a.size(cx).align_to(b.default_align(cx).abi) };
         self.scalar_gcc_type_at(cx, scalar, offset)
     }