[test] Fix test/IRGen/metadata.swift to match the correct symbol

When this test was updated for new platforms it was accidentally changed
to match the _METACLASS_DATA symbol instead of the _DATA symbol. Fix
that and update the flags to match. This lets us remove the instance
start value 40 from the checks, so the test now matches the comment
saying it should be 8 or 16.

rdar://135453916

Author: benlangmuir

test/IRGen/metadata.swift

@@ -10,10 +10,10 @@ enum Singleton {
 
 // CHECK: @"$s1A1GC14zeroSizedFieldAA9SingletonOvpWvd" = hidden constant i{{(64|32)}} 0
 // Check that the instance start is after the header (at 8 or 16).
-// CHECK-macosx: _DATA__TtC1A1G = internal constant {{.*}} { i32 {{(128|129)}}, i32 {{(16|8|40)}}
-// CHECK-ios: _DATA__TtC1A1G = internal constant {{.*}} { i32 {{(128|129)}}, i32 {{(16|8|40)}}
-// CHECK-watchos: _DATA__TtC1A1G = internal constant {{.*}} { i32 {{(128|129)}}, i32 {{(16|8|40)}}
-// CHECK-tvos: _DATA__TtC1A1G = internal constant {{.*}} { i32 {{(128|129)}}, i32 {{(16|8|40)}}
+// CHECK-macosx: @_DATA__TtC1A1G = internal constant {{.*}} { i32 {{(128|192)}}, i32 {{(16|8)}}
+// CHECK-ios: @_DATA__TtC1A1G = internal constant {{.*}} { i32 {{(128|192)}}, i32 {{(16|8)}}
+// CHECK-watchos: @_DATA__TtC1A1G = internal constant {{.*}} { i32 {{(128|192)}}, i32 {{(16|8)}}
+// CHECK-tvos: @_DATA__TtC1A1G = internal constant {{.*}} { i32 {{(128|192)}}, i32 {{(16|8)}}
 
 class G {
   var zeroSizedField = Singleton.only