[Coverage] Avoid unnecessary copying of std::vector
[Coverage] Avoid unnecessary copying of std::vector

Approved by: Justin Bogner <mail@justinbogner.com>

Differential Revision: http://reviews.llvm.org/D18756

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@266284 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 78732b7659b39bcc886d89e624e4b628ae33b287)

apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm