Removed spurious lookup of the $__lldb_expr
selector when compiling an expression in an
Objective-C context.

<rdar://problem/15797390>


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@200950 91177308-0d34-0410-b5e6-96231b3b80d8
Lock the JIT before using it.

<rdar://problem/15958296>


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@200951 91177308-0d34-0410-b5e6-96231b3b80d8