fixup macOS gtest running
fixup macOS gtest running

Needed to explicitly turn off RTTI (since lldb-core builds
with -fno-rtti) and specify -DGTEST_HAVE_RTTI=0.

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@279205 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb