Changes imported from Abseil "staging" branch:

- bb743d8b2017dc1ac181e9d2a90728b45eef344b Internal change. by Daniel Katz <katzdm@google.com>
  - a884af8e2bd70818168aad693b70b8fe98e96bcb Rearrange file comment. by Alex Strelnikov <strel@google.com>
  - 5ed241ef4d5bdc1ef52f7bca9c6ff42d0448e9f4 Internal change. by Alex Strelnikov <strel@google.com>
  - 04d44c8982d7b3077cae5e6189cb512818ce016b Add experiment documentation for MallocExtension API. by Chris Kennelly <ckennelly@google.com>

GitOrigin-RevId: bb743d8b2017dc1ac181e9d2a90728b45eef344b
Change-Id: Ia3ac079fc16b421a0f36be7dc0167045b92e417d

absl/numeric/int128.h

@@ -17,9 +17,10 @@
 // File: int128.h
 // -----------------------------------------------------------------------------
 //
-// This header file defines 128-bit integer types. Currently, this file defines
-// `uint128`, an unsigned 128-bit integer; a signed 128-bit integer is
-// forthcoming.
+// This header file defines 128-bit integer types.
+//
+// Currently, this file defines `uint128`, an unsigned 128-bit integer; a signed
+// 128-bit integer is forthcoming.
 
 #ifndef ABSL_NUMERIC_INT128_H_
 #define ABSL_NUMERIC_INT128_H_
@@ -37,6 +38,7 @@
 
 namespace absl {
 
+
 // uint128
 //
 // An unsigned 128-bit integer type. The API is meant to mimic an intrinsic type