[CMake] Use ABI version 2 for C++ library in Fuchsia
[CMake] Use ABI version 2 for C++ library in Fuchsia

Fuchsia has always been using ABI version 2 but I forgot this option
when setting up the cache file for runtimes build.

Differential Revision: https://reviews.llvm.org/D35705

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@308705 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang