RFR: 8255416: Investigate err_msg to detect unnecessary uses [v2]

[Anton Kozlov]

> Hi,
> 
> When a single string without formatting arguments is provided to `err_msg`, it's redundancy, as the same message could be used without any err_msg. This is a follow-up to the discussion https://github.com/openjdk/jdk/pull/812#discussion_r511784050
> 
> Please review a change that makes `err_msg` with a single string to fail compilation. 
> 
> Detected uses of err_msg with a single string were eliminated as well.

Anton Kozlov has updated the pull request incrementally with one additional commit since the last revision:

  Fix codestyle

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/905/files
  - new: https://git.openjdk.java.net/jdk/pull/905/files/93af93b0..52ff2ccb

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=905&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=905&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/905.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/905/head:pull/905

PR: https://git.openjdk.java.net/jdk/pull/905