Revert "Enable dex2oat swap test for CC on x86."

Is't still failing and the difference can be
rather huge:
    Expected: (native_alloc_2_) < (native_alloc_1_),
    actual: 379712 vs 248600

Bug: 29259363

This reverts commit 38f5663a970b633f08e144b4dff33633c51352ee.

Change-Id: Ie1d62fbba688aeadffb9d5aafd5b9cf632742ed6
diff --git a/dex2oat/dex2oat_test.cc b/dex2oat/dex2oat_test.cc
index e208337..90b4955 100644
--- a/dex2oat/dex2oat_test.cc
+++ b/dex2oat/dex2oat_test.cc
@@ -399,6 +399,11 @@
 };
 
 TEST_F(Dex2oatSwapUseTest, CheckSwapUsage) {
+  // The `native_alloc_2_ >= native_alloc_1_` assertion below may not
+  // hold true on some x86 systems when read barriers are enabled;
+  // disable this test while we investigate (b/29259363).
+  TEST_DISABLED_FOR_READ_BARRIER_ON_X86();
+
   RunTest(false /* use_fd */,
           false /* expect_use */);
   GrabResult1();
diff --git a/runtime/common_runtime_test.h b/runtime/common_runtime_test.h
index 26ec364..17e3729 100644
--- a/runtime/common_runtime_test.h
+++ b/runtime/common_runtime_test.h
@@ -223,6 +223,12 @@
     return; \
   }
 
+#define TEST_DISABLED_FOR_READ_BARRIER_ON_X86() \
+  if (kUseReadBarrier && kRuntimeISA == kX86) { \
+    printf("WARNING: TEST DISABLED FOR READ BARRIER ON X86\n"); \
+    return; \
+  }
+
 #define TEST_DISABLED_FOR_STRING_COMPRESSION() \
   if (mirror::kUseStringCompression) { \
     printf("WARNING: TEST DISABLED FOR STRING COMPRESSION\n"); \