RFR: JDK-8280745: Allow SuppressWarnings to be used in package declarations [v3]

[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 incrementally with one additional commit since the last revision:

  Respond to CSR feedback.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7239/files
  - new: https://git.openjdk.java.net/jdk/pull/7239/files/653a14ae..2339a085

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7239&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7239&range=01-02

  Stats: 27 lines in 1 file changed: 9 ins; 8 del; 10 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