Explicitly pass Thread::Current to MutexLock and Alloc.

Change-Id: I8b75bc0617915465f102815b32306aa7760dcae4
diff --git a/src/compiler_llvm/compiler_llvm.cc b/src/compiler_llvm/compiler_llvm.cc
index f65f684..85ae794 100644
--- a/src/compiler_llvm/compiler_llvm.cc
+++ b/src/compiler_llvm/compiler_llvm.cc
@@ -126,7 +126,7 @@
 
 
 CompilationUnit* CompilerLLVM::AllocateCompilationUnit() {
-  MutexLock GUARD(num_cunits_lock_);
+  MutexLock GUARD(Thread::Current(), num_cunits_lock_);
   CompilationUnit* cunit = new CompilationUnit(this, num_cunits_++);
   if (!bitcode_filename_.empty()) {
     cunit->SetBitcodeFileName(StringPrintf("%s-%zu", bitcode_filename_.c_str(), num_cunits_-1));