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/arm64/int_arm64.cc b/compiler/dex/quick/arm64/int_arm64.cc
index 6be66a2..e8f5cb9 100644
--- a/compiler/dex/quick/arm64/int_arm64.cc
+++ b/compiler/dex/quick/arm64/int_arm64.cc
@@ -163,8 +163,7 @@
 
 LIR* Arm64Mir2Lir::OpCmpMemImmBranch(ConditionCode cond, RegStorage temp_reg,
                                      RegStorage base_reg, int offset, int check_value,
-                                     LIR* target, LIR** compare) {
-  DCHECK(compare == nullptr);
+                                     LIR* target) {
   // It is possible that temp register is 64-bit. (ArgReg or RefReg)
   // Always compare 32-bit value no matter what temp_reg is.
   if (temp_reg.Is64Bit()) {