RFR: 7903758: jextract should avoid temporary file creation [v2]

[Athijegannathan Sundararajan]

> jextract creates a temporary file to support multiple headers and special header syntax <foo.h>. This patch avoids that temporary file creation by using clang's in-memory parsing API clang_createTranslationUnitFromSourceFile

Athijegannathan Sundararajan has updated the pull request incrementally with one additional commit since the last revision:

  fixed Windows clang dll name.

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Changes:
  - all: https://git.openjdk.org/jextract/pull/251/files
  - new: https://git.openjdk.org/jextract/pull/251/files/82011879..ed14dea8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jextract&pr=251&range=01
 - incr: https://webrevs.openjdk.org/?repo=jextract&pr=251&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jextract/pull/251.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/251/head:pull/251

PR: https://git.openjdk.org/jextract/pull/251