Fix build of lldb on Mavericks after svn rev.243511.

This patch adds a test for ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED
around the code which requires 10.10 support to link. Without this, lldb
gets unresolved references to _csr_check and _rootless_allows_task_for_pid.

Reviewed by: jasonmolenda
Subscribers: lldb-commits
Differential Revision: http://reviews.llvm.org/D11668

llvm-svn: 243715