[lworld] RFR: 8368475: [lworld] Add preview classes to jimage at make time [v4]

[David Beaumont]

> Copies valuetype classes for each module into corresponding "/META-INF/preview/..." sub-directories to be pulled into jimage files and processed by the new preview mode handling code.
> 
> There might be a better way to do this in terms of Makefile semantics, but this seems to work well enough and doesn't prevent the value-class JAR files being generated for patching (which is still how everyone will get value classes until the rest of the work is plumbed in).
> 
> To enable the new preview mode work, set the "DISABLE_PREVIEW_PATCHING" system property to "true".

David Beaumont has updated the pull request incrementally with one additional commit since the last revision:

  added notes for what needs fixing later

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

Changes:
  - all: https://git.openjdk.org/valhalla/pull/1727/files
  - new: https://git.openjdk.org/valhalla/pull/1727/files/291c1c74..f3ce482f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1727&range=03
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1727&range=02-03

  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/valhalla/pull/1727.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1727/head:pull/1727

PR: https://git.openjdk.org/valhalla/pull/1727