Reland [libc++] [P0325] Implement to_array from LFTS with updates.

Fixed expected errors and notes.

Summary:
This patch implements https://wg21.link/P0325.

Reviewers: EricWF, mclow.lists, ldionne, lichray

Reviewed By: ldionne, lichray

Subscribers: lichray, dexonsmith, zoecarver, christof, ldionne, libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D69882
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index a6191a5..faec065 100755
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -586,6 +586,12 @@
    },
    "headers": ["bit"],
    },
+  {"name": "__cpp_lib_to_array",
+   "values": {
+     "c++2a": 201907L,
+   },
+   "headers": ["array"],
+   },
 ]], key=lambda tc: tc["name"])
 
 def get_std_dialects():