Do not use default initializer for union

The next Clang update complains about this code pattern. Rewrite default
constructor to explicitly initialize the union field instead of using
the default initializer.

Test: Build
Bug: 37752547
Change-Id: I22a2aa392d7f4803282baed832b0fa2f852016ac
(cherry picked from commit 4fdbdd1692a549a31382f33f5d529fd141453ea1)
1 file changed