Reland "Fix array-of-vector comparisons in Metal."

This reverts commit ef9a1b66d060dfbbd58859b3401e278611b55308.

Reason for revert: not broken after all

Original change's description:
> Revert "Fix array-of-vector comparisons in Metal."
>
> This reverts commit 130338c9e1bc90afc63424115a6a8a842d43ddd5.
>
> Reason for revert: SkSL_ArrayComparison test causes Adreno 630/640 to crash in Vulkan
>
> Original change's description:
> > Fix array-of-vector comparisons in Metal.
> >
> > Comparing `vec1 == vec2` returns a bvec in Metal, so the result must be
> > wrapped in `all()` in order to boil it down to a single boolean result.
> > Our array-comparison helper function did not do this. Fortunately,
> > `all(scalar)` is a no-op, so we can just wrap the result unilaterally.
> >
> > Change-Id: I4f1f09a6832164ae2e6577d53b317f561332d581
> > Bug: skia:12324
> > Reviewed-on: https://skia-review.googlesource.com/c/skia/+/437736
> > Auto-Submit: John Stiles <johnstiles@google.com>
> > Commit-Queue: Brian Osman <brianosman@google.com>
> > Reviewed-by: Brian Osman <brianosman@google.com>
>
> TBR=brianosman@google.com,ethannicholas@google.com,johnstiles@google.com,skcq-be@skia-corp.google.com.iam.gserviceaccount.com
>
> Change-Id: Ic76a5527a8339c8201f52df08d43041d7dcbeb61
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: skia:12324
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/438077
> Reviewed-by: John Stiles <johnstiles@google.com>
> Commit-Queue: John Stiles <johnstiles@google.com>

# Not skipping CQ checks because this is a reland.

Bug: skia:12324
Change-Id: I3da699b8d1113800efb27e162d0c6315f0aeaa49
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/438176
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
diff --git a/src/sksl/codegen/SkSLMetalCodeGenerator.cpp b/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
index 2ba42f4..1cb0053 100644
--- a/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
+++ b/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
@@ -1350,7 +1350,7 @@
 template <typename T1, typename T2, size_t N>
 bool operator==(thread const array<T1, N>& left, thread const array<T2, N>& right) {
     for (size_t index = 0; index < N; ++index) {
-        if (!(left[index] == right[index])) {
+        if (!all(left[index] == right[index])) {
             return false;
         }
     }