[LoopVectorize] Convert test to opaque pointers (NFC)

I'm keeping the bitcast in the input here, because without it
we end up introducing a stride 1 assumption and end up testing
a different case.

Author: nikic

llvm/test/Transforms/LoopVectorize/SystemZ/load-scalarization-cost-0.ll

@@ -1,20 +1,20 @@
-; RUN: opt -opaque-pointers=0 -mtriple=s390x-unknown-linux -mcpu=z13 -passes=loop-vectorize \
+; RUN: opt -mtriple=s390x-unknown-linux -mcpu=z13 -passes=loop-vectorize \
 ; RUN:   -force-vector-width=2 -debug-only=loop-vectorize \
 ; RUN:   -disable-output < %s 2>&1 | FileCheck %s
 ; REQUIRES: asserts
 ;
 ; Check that a scalarized load does not get operands scalarization costs added.
 
-define void @fun(i64* %data, i64 %n, i64 %s, double* %Src) {
+define void @fun(ptr %data, i64 %n, i64 %s, ptr %Src) {
 entry:
   br label %for.body
 
 for.body:
   %iv = phi i64 [ 0, %entry ], [ %iv.next, %for.body ]
   %mul = mul nsw i64 %iv, %s
-  %gep = getelementptr inbounds double, double* %Src, i64 %mul
-  %bct = bitcast double* %gep to i64*
-  %ld = load i64, i64* %bct
+  %gep = getelementptr inbounds double, ptr %Src, i64 %mul
+  %bct = bitcast ptr %gep to ptr
+  %ld = load i64, ptr %bct
   %iv.next = add nuw nsw i64 %iv, 1
   %cmp110.us = icmp slt i64 %iv.next, %n
   br i1 %cmp110.us, label %for.body, label %for.end
@@ -23,5 +23,5 @@ for.end:
   ret void
 
 ; CHECK: LV: Found an estimated cost of 2 for VF 2 For instruction:   %mul = mul nsw i64 %iv, %s
-; CHECK: LV: Found an estimated cost of 2 for VF 2 For instruction:   %ld = load i64, i64* %bct
+; CHECK: LV: Found an estimated cost of 2 for VF 2 For instruction:   %ld = load i64, ptr %bct
 }