src: remove empty comment in node_http2.h

This commit removes an "empty" comment in node_http2.h that I don't
think was intentional and as far as I can tell not a doxygen comment or
anything like that.

This was not picked up by the cpp linter so a suggestion has also been
added to the CheckComment function to detect these in the future.

PR-URL: nodejs/node#16400
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

src/node_http2.h

@@ -333,7 +333,6 @@ class Http2Options {
 
 static const size_t kAllocBufferSize = 64 * 1024;
 
-////
 typedef uint32_t(*get_setting)(nghttp2_session* session,
                                nghttp2_settings_id id);
 

tools/cpplint.py

@@ -3021,7 +3021,7 @@ def CheckComment(line, filename, linenum, next_line_start, error):
       # If the comment contains an alphanumeric character, there
       # should be a space somewhere between it and the // unless
       # it's a /// or //! Doxygen comment.
-      if (Match(r'//[^ ]*\w', comment) and
+      if (Match(r'(?://[^ ]*\w)|(?:////\s*$)', comment) and
           not Match(r'(///|//\!)(\s+|$)', comment)):
         error(filename, linenum, 'whitespace/comments', 4,
               'Should have a space between // and comment')