RFR: Merge jdk

[Mikael Vidstedt]

Merge in jdk-16+12

-------------

Commit messages:
 - Merge jdk
 - 8251499: no-placeholder compact number patterns throw IllegalArgumentException
 - 8251490: [TESTBUG] The Java thread stack size specified is too small for nsk/stress/stack. Specify at least 448k
 - 8251454: Wrong "self type" in DCTree.DCEndElement
 - 8251357: [DocCommentParser] Infinite loop while looking for the end of a preamble
 - 8246047: Replace LinkedList impl in net.http.websocket.BuilderImpl
 - 8251888: Move HotSpot Style Guide wiki subpages to jdk/jdk/doc
 - 8251715: Throw UncheckedIOException in place of InternalError when HttpClient fails due to unavailability of underlying resources required by SSLContext
 - 8250748: Doc of URL(String, String, int, String, URLStreamHandler) does not use link
 - 8249902: tools/javac/records/mandated_members/read_resolve_method/CheckReadResolveMethodTest.java uses @ignore w/o bug-id
 - ... and 516 more: https://git.openjdk.java.net/portola/compare/45171054...c0fc2582

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.java.net/portola/11/webrev.00.0
 - jdk: https://webrevs.openjdk.java.net/portola/11/webrev.00.1

Changes: https://git.openjdk.java.net/portola/pull/11/files
  Stats: 53394 lines in 5602 files changed: 27056 ins; 14201 del; 12137 mod
  Patch: https://git.openjdk.java.net/portola/pull/11.diff
  Fetch: git fetch https://git.openjdk.java.net/portola pull/11/head:pull/11

PR: https://git.openjdk.java.net/portola/pull/11