reflect: record unsafe.Pointer, not uintptr, during DeepEqual

This is more correct with respect to garbage collection.
I don't know of any specific failures it could cause today.

Change-Id: I7eed6a06d2f281051199e79e4a9913aa8360ded7
Reviewed-on: https://go-review.googlesource.com/14137Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/reflect/deepequal.go

@@ -6,13 +6,15 @@
 
 package reflect
 
+import "unsafe"
+
 // During deepValueEqual, must keep track of checks that are
 // in progress.  The comparison algorithm assumes that all
 // checks in progress are true when it reencounters them.
 // Visited comparisons are stored in a map indexed by visit.
 type visit struct {
-	a1  uintptr
-	a2  uintptr
+	a1  unsafe.Pointer
+	a2  unsafe.Pointer
 	typ Type
 }
 
@@ -37,9 +39,9 @@ func deepValueEqual(v1, v2 Value, visited map[visit]bool, depth int) bool {
 	}
 
 	if v1.CanAddr() && v2.CanAddr() && hard(v1.Kind()) {
-		addr1 := v1.UnsafeAddr()
-		addr2 := v2.UnsafeAddr()
-		if addr1 > addr2 {
+		addr1 := unsafe.Pointer(v1.UnsafeAddr())
+		addr2 := unsafe.Pointer(v2.UnsafeAddr())
+		if uintptr(addr1) > uintptr(addr2) {
 			// Canonicalize order to reduce number of entries in visited.
 			addr1, addr2 = addr2, addr1
 		}