Don't require AVX registers if the target CPU doesn't have them
Don't require AVX registers if the target CPU doesn't have them

TestLldbGdbServer was failing because it always assumed AVX is available on
x86_64 Linux. This patch checks the target before asserting that AVX
registers are available.



git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@232137 91177308-0d34-0410-b5e6-96231b3b80d8

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