RFR: 7903758: jextract should avoid temporary file creation [v6]

[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:

  removed temporary empty file usage in MacroParserImpl

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Changes:
  - all: https://git.openjdk.org/jextract/pull/251/files
  - new: https://git.openjdk.org/jextract/pull/251/files/76709f6e..6b22878d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jextract&pr=251&range=05
 - incr: https://webrevs.openjdk.org/?repo=jextract&pr=251&range=04-05

  Stats: 9 lines in 2 files changed: 0 ins; 2 del; 7 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