Revert "Add implicit null and stack checks for x86"

It breaks cross compilation with x86_64.

This reverts commit 34e826ccc80dc1cf7c4c045de6b7f8360d504ccf.

Change-Id: I34ba07821fc0a022fda33a7ae21850957bbec5e7
diff --git a/compiler/dex/quick/codegen_util.cc b/compiler/dex/quick/codegen_util.cc
index 1ac4707..5870d22 100644
--- a/compiler/dex/quick/codegen_util.cc
+++ b/compiler/dex/quick/codegen_util.cc
@@ -1162,12 +1162,9 @@
 }
 
 LIR *Mir2Lir::OpCmpMemImmBranch(ConditionCode cond, RegStorage temp_reg, RegStorage base_reg,
-                                int offset, int check_value, LIR* target, LIR** compare) {
+                                int offset, int check_value, LIR* target) {
   // Handle this for architectures that can't compare to memory.
-  LIR* inst = Load32Disp(base_reg, offset, temp_reg);
-  if (compare != nullptr) {
-    *compare = inst;
-  }
+  Load32Disp(base_reg, offset, temp_reg);
   LIR* branch = OpCmpImmBranch(cond, temp_reg, check_value, target);
   return branch;
 }