[LibTooling] Fix build breakage from commit 7b7ce6683ee.

On configurations with -Werror,-Wmissing-field-initializers, the commit does not compile. This commit fixes the offending line.

Original Differential Revision: https://reviews.llvm.org/D60408

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@358705 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed