RFR: 8255757: Javac emits duplicate pool entries on array::clone [v2]

[Guoxiong Li]

> Hi all,
> 
> Currently, javac would emit duplicate pool entries when compiling array::clone.
> This patch fixes it by using a cached field `Map<Type, Symbol> qualifiedSymbolCache;` and adds a corresponding test case.
> 
> Thank you for taking the time to review.
> 
> Best Regards.

Guoxiong Li has updated the pull request incrementally with one additional commit since the last revision:

  Cleanup variable and useless test code.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1912/files
  - new: https://git.openjdk.java.net/jdk/pull/1912/files/ccad077d..1ab79ce1

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1912&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1912&range=00-01

  Stats: 3 lines in 2 files changed: 1 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1912.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1912/head:pull/1912

PR: https://git.openjdk.java.net/jdk/pull/1912