RFR: 8288082: Build failure due to __clang_major__ is not defined after JDK-8214976

[Jie Fu]

Hi all,

Build failure was observed when build on a machine without clang.
Please review this trivial patch which fixes the build failure due to `__clang_major__` is not defined.

Thanks.
Best regards,
Jie

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

Commit messages:
 - 8288082: Build failure due to __clang_major__ is not defined after JDK-8214976

Changes: https://git.openjdk.java.net/jdk/pull/9096/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=9096&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288082
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/9096.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/9096/head:pull/9096

PR: https://git.openjdk.java.net/jdk/pull/9096