[lldb] Unbreak lldb builds due to r327219

Summary:
r327219 adds wrappers to sort which shuffle the container before sorting.
This causes lldb bots to break as the call to sort is now ambiguous:
http://lab.llvm.org:8011/builders/lldb-x86_64-ubuntu-14.04-buildserver/builds/20725/steps/ninja%20build%20local/logs/stdio

So we need use llvm::sort instead of sort to avoid ambiguity with std::sort.

Note: This patch is just to unbreak the bots. I plan to have subsequent patches which will convert all
calls to std::sort to llvm::sort.

Reviewers: RKSimon, k8stone, jingham, labath, zturner

Subscribers: andreadb, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D44354

llvm-svn: 327224