RFR: JDK-8280744: Allow SuppressWarnings to be used in package declarations [v4]

[Joe Darcy]

> The SuppressWarnings annotation type is declared have multiple targets, including modules; however, "package" is left off of its target list. As package-info file are another kind of declaration where a compiler could give warnings, allowing SuppressWarnings in that case is reasonable. Wanting SuppressWarnings in package-info file came up while working on doclint warnings (JDK-8280534). 
> 
> Please also review the companion CSR:
> https://bugs.openjdk.java.net/browse/JDK-8280745
> 
> While the SuppressWarnings annotation does have a JLS section (9.6.4.5. @SuppressWarnings), the section doesn't mention the target list therefore doesn't appear to need to be updated.

Joe Darcy has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Respond to review feedback.
 - Merge branch 'master' into JDK-8280744
 - Respond to CSR feedback.
 - Respond to review feedback.
 - JDK-8280745: Allow SuppressWarnings to be used in package declarations

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7239/files
  - new: https://git.openjdk.java.net/jdk/pull/7239/files/2339a085..7b04321c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7239&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7239&range=02-03

  Stats: 2656 lines in 124 files changed: 1495 ins; 647 del; 514 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7239.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7239/head:pull/7239

PR: https://git.openjdk.java.net/jdk/pull/7239