RFR: 8302667: Improve message format when failing to load symbols or libraries [v3]

[Julian Waters]

> DLL_ERROR4 is a macro expanding to an error message when a failure to load a generic item (shared libraries or an exported symbol from said libraries for example) occurs. "Error: loading:" is not a very pretty message, so this small change results in "Error: Failed to load %s" instead, which looks better and also means the message makes more sense if we want to append a reason behind as well, such as "Error: Failed to load libjvm.so because xxx"

Julian Waters has updated the pull request incrementally with two additional commits since the last revision:

 - expandArgFile
 - ARG_ERROR18

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/12596/files
  - new: https://git.openjdk.org/jdk/pull/12596/files/5f4370f8..6b54816a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12596&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12596&range=01-02

  Stats: 2 lines in 2 files changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12596.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12596/head:pull/12596

PR: https://git.openjdk.org/jdk/pull/12596