Revert "x86/x86-64: Avoid temporary for read barrier field load."

Fault handler does not recognize the instruction
    F6 /0 ib    TEST r/m8, imm8
so we get crashes instead of NPEs.

Bug: 29966877
Bug: 12687968

This reverts commit ccf06d8f19a37432de4a3b768747090adfbd18ec.

Change-Id: Ib7db3b59f44c0d3ed5e24a20b6c6ee596a89d709
diff --git a/compiler/optimizing/code_generator_x86.h b/compiler/optimizing/code_generator_x86.h
index c644e40..894f2e8 100644
--- a/compiler/optimizing/code_generator_x86.h
+++ b/compiler/optimizing/code_generator_x86.h
@@ -254,7 +254,8 @@
   void GenerateReferenceLoadTwoRegisters(HInstruction* instruction,
                                          Location out,
                                          Location obj,
-                                         uint32_t offset);
+                                         uint32_t offset,
+                                         Location maybe_temp);
   // Generate a GC root reference load:
   //
   //   root <- *address
@@ -486,6 +487,7 @@
                                              Location ref,
                                              Register obj,
                                              uint32_t offset,
+                                             Location temp,
                                              bool needs_null_check);
   // Fast path implementation of ReadBarrier::Barrier for a heap
   // reference array load when Baker's read barriers are used.
@@ -494,6 +496,7 @@
                                              Register obj,
                                              uint32_t data_offset,
                                              Location index,
+                                             Location temp,
                                              bool needs_null_check);
   // Factored implementation used by GenerateFieldLoadWithBakerReadBarrier
   // and GenerateArrayLoadWithBakerReadBarrier.
@@ -501,6 +504,7 @@
                                                  Location ref,
                                                  Register obj,
                                                  const Address& src,
+                                                 Location temp,
                                                  bool needs_null_check);
 
   // Generate a read barrier for a heap reference within `instruction`