Allow for 5200 words in dump-words-to-file

After switching to OpenJdk,  doc-comment-check target
started to fail due to "Too many words (5082)" while
generating out/target/common/docs/doc-comment-check-timestamp.rsp
This change extends number of dumped words to 5200.

Bug: 25758743
Change-Id: Ifdc23d57c888c83533d237dd0a3bdafd20912cdf