Enable multi-threaded Quick compilation

Reuse thread-local copies of llvm context data for Quick compiler
(while continuing to regenerate fresh ones per method for Portable).
This is a transitional CL - the upcoming compiler driver change
is expected to pass pass a thread context structure to each compiler
worker thread rather than use the pthread_key mechanism.

Change-Id: I277920a5c2705748c3a9f37ceace53c903747ec2
diff --git a/src/compiler/CompilerIR.h b/src/compiler/CompilerIR.h
index 593fce5..5a10831 100644
--- a/src/compiler/CompilerIR.h
+++ b/src/compiler/CompilerIR.h
@@ -549,7 +549,7 @@
   Checkstats* checkstats;
 #if defined(ART_USE_QUICK_COMPILER)
   bool genBitcode;
-  QuickCompiler* quick_compiler;
+  LLVMInfo* llvm_info;
   llvm::LLVMContext* context;
   llvm::Module* module;
   llvm::Function* func;