Add a lock to PlatformPOSIX::DoLoadImage

Summary:
Multiple threads could be calling into DoLoadImage concurrently,
only one should be allowed to create the UtilityFunction.

Reviewers: jingham

Subscribers: emaste, lldb-commits

Differential Revision: https://reviews.llvm.org/D46733

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@332115 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed