Changes imported from Abseil "staging" branch:

- 7349efb2d18db3a019034f66502b67f7461c15ae Reword the noexcept specification for InlinedVector's def... by Jon Cohen <cohenjon@google.com>
  - f3576b18d039a0c8b533f05ac496fa8d7ff3b207 Remove an unneeded comment in call_once.h by Jon Cohen <cohenjon@google.com>

GitOrigin-RevId: 7349efb2d18db3a019034f66502b67f7461c15ae
Change-Id: I398888e6a82ccd69e23ffc0af9eb198d25e57e02

absl/base/call_once.h

@@ -43,7 +43,6 @@ namespace absl {
 class once_flag;
 
 namespace base_internal {
-// Implementation detail.
 std::atomic<uint32_t>* ControlWord(absl::once_flag* flag);
 }  // namespace base_internal
 

absl/container/inlined_vector.h

@@ -82,8 +82,7 @@ class InlinedVector {
   using reverse_iterator = std::reverse_iterator<iterator>;
   using const_reverse_iterator = std::reverse_iterator<const_iterator>;
 
-  InlinedVector() noexcept(
+  InlinedVector() noexcept(noexcept(allocator_type()))
-      std::is_nothrow_default_constructible<allocator_type>::value)
       : allocator_and_tag_(allocator_type()) {}
 
   explicit InlinedVector(const allocator_type& alloc) noexcept