[libc++][NFC] Remove #endif comments for really small conditionals on _LIBCPP_HAS_NO_UNICODE_CHARS

We generally don't put a comment on the #endif when the #if block is so small
that it's unambiguous what the #endif refers to.

NOKEYCHECK=True
GitOrigin-RevId: 71752e00081cb4bc55d60c186cce1a18ed12e405
diff --git a/include/__config b/include/__config
index 2a63641..d7d37bd 100644
--- a/include/__config
+++ b/include/__config
@@ -789,7 +789,7 @@
 #ifdef _LIBCPP_HAS_NO_UNICODE_CHARS
 typedef unsigned short char16_t;
 typedef unsigned int   char32_t;
-#endif // _LIBCPP_HAS_NO_UNICODE_CHARS
+#endif
 
 #ifndef __SIZEOF_INT128__
 #define _LIBCPP_HAS_NO_INT128
diff --git a/include/cstddef b/include/cstddef
index 1b54e7b..551bd83 100644
--- a/include/cstddef
+++ b/include/cstddef
@@ -65,7 +65,7 @@
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 template <>          struct __libcpp_is_integral<char16_t>           { enum { value = 1 }; };
 template <>          struct __libcpp_is_integral<char32_t>           { enum { value = 1 }; };
-#endif // _LIBCPP_HAS_NO_UNICODE_CHARS
+#endif
 template <>          struct __libcpp_is_integral<short>              { enum { value = 1 }; };
 template <>          struct __libcpp_is_integral<unsigned short>     { enum { value = 1 }; };
 template <>          struct __libcpp_is_integral<int>                { enum { value = 1 }; };
diff --git a/include/iosfwd b/include/iosfwd
index 499839f..974cb42 100644
--- a/include/iosfwd
+++ b/include/iosfwd
@@ -227,7 +227,7 @@
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 typedef fpos<mbstate_t>    u16streampos;
 typedef fpos<mbstate_t>    u32streampos;
-#endif // _LIBCPP_HAS_NO_UNICODE_CHARS
+#endif
 
 #if defined(_NEWLIB_VERSION)
 // On newlib, off_t is 'long int'
diff --git a/include/string b/include/string
index 8696bdf..4ca0e86 100644
--- a/include/string
+++ b/include/string
@@ -675,7 +675,7 @@
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 typedef basic_string<char16_t> u16string;
 typedef basic_string<char32_t> u32string;
-#endif // _LIBCPP_HAS_NO_UNICODE_CHARS
+#endif
 
 template<class _CharT, class _Traits, class _Allocator>
 class