RFR: 8252995: Non-PCH builds broken by JDK-8250961

[Kim Barrett]

8252995: Non-PCH builds broken by JDK-8250961

Please review this trivial fix for no-PCH build failures, introduced by
JDK-8250961.

Only one file _requires_ an additional #include.  There are other files that
were modified by that change that probably should have had an include added,
on the "include what you use" theory.  But in the interest of faster
turn-around to fix the build failure, I'm not dealing with any of those in
this change.

Testing:
local (linux-x64) no-pch build with shenandoah included
mach5 builds-tier1 (in progress)

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

Commit messages:
 - add missing include

Changes: https://git.openjdk.java.net/jdk/pull/107/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=107&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8252995
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/107.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/107/head:pull/107

PR: https://git.openjdk.java.net/jdk/pull/107