[jdk21u] RFR: 8312467: relax the builddir check in make/autoconf/basic.m4

[Matthias Baesken]

8312467: relax the builddir check in make/autoconf/basic.m4

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Commit messages:
 - Backport 6e3cc131daa9f3b883164333bdaad7aa3a6ca018

Changes: https://git.openjdk.org/jdk21u/pull/233/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=233&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8312467
  Stats: 6 lines in 1 file changed: 1 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk21u/pull/233.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/233/head:pull/233

PR: https://git.openjdk.org/jdk21u/pull/233