Fix test to call clear system state in convolve_test.

Assembly tests should clear system state, as we have no
expectation of proper system state in between test runs..

Change-Id: I0f591996c1f17ef2a5a8572a6b445f757223a144

test/convolve_test.cc

@@ -10,6 +10,7 @@
 
 #include <string.h>
 #include "test/acm_random.h"
+#include "test/clear_system_state.h"
 #include "test/register_state_check.h"
 #include "test/util.h"
 #include "third_party/googletest/src/include/gtest/gtest.h"
@@ -315,6 +316,8 @@ class ConvolveTest : public ::testing::TestWithParam<ConvolveParam> {
 #endif
   }
 
+  virtual void TearDown() { libvpx_test::ClearSystemState(); }
+
   static void TearDownTestCase() {
     vpx_free(input_ - 1);
     input_ = NULL;