RFR: 8291917: [WINDOWS] Dump error diagnostics when runtime libraries fail to load

[Julian Waters]

Please review a small patch for dumping the failure reason when the MSVCRT libraries or the JVM fails to load on Windows, which have been very helpful in my personal fork of the JDK so far This also fixes a small bug in the Windows implementation of JLI_ErrorMessageSys where C runtime errors are never written to stderr.

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

Commit messages:
 - LoadLibrary checks should explicitly use NULL
 - Dump error (if any) when libraries fail to load
 - Prettify DLL_ERROR4

Changes: https://git.openjdk.org/jdk/pull/9749/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9749&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291917
  Stats: 19 lines in 2 files changed: 0 ins; 6 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/9749.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9749/head:pull/9749

PR: https://git.openjdk.org/jdk/pull/9749