avg_test: fix allocation check

move check on source_data_ before memset
+ normalize allocation checks in this file to use ASSERT_NE(...,
  nullptr)

Change-Id: I4c21a1b7d4513561c0277426e7f832486a8e7285
diff --git a/test/avg_test.cc b/test/avg_test.cc
index d187760..ca24c9b 100644
--- a/test/avg_test.cc
+++ b/test/avg_test.cc
@@ -57,8 +57,8 @@
 
     source_data_ = static_cast<Pixel *>(
         aom_memalign(kDataAlignment, kDataBlockSize * sizeof(source_data_[0])));
+    ASSERT_NE(source_data_, nullptr);
     memset(source_data_, 0, kDataBlockSize * sizeof(source_data_[0]));
-    ASSERT_TRUE(source_data_ != NULL);
     source_stride_ = (width_ + 31) & ~31;
     bit_depth_ = 8;
     rnd_.Reset(ACMRandom::DeterministicSeed());
@@ -362,7 +362,7 @@
   virtual void SetUp() {
     source_data_ = static_cast<uint8_t *>(
         aom_memalign(kDataAlignment, kDataBlockSize * sizeof(source_data_[0])));
-    ASSERT_TRUE(source_data_ != NULL);
+    ASSERT_NE(source_data_, nullptr);
 
     hbuf_asm_ = static_cast<int16_t *>(
         aom_memalign(kDataAlignment, sizeof(*hbuf_asm_) * 16));
@@ -535,10 +535,10 @@
 
     ref_vector = static_cast<int16_t *>(
         aom_memalign(kDataAlignment, width * sizeof(ref_vector[0])));
-    ASSERT_TRUE(ref_vector != NULL);
+    ASSERT_NE(ref_vector, nullptr);
     src_vector = static_cast<int16_t *>(
         aom_memalign(kDataAlignment, width * sizeof(src_vector[0])));
-    ASSERT_TRUE(src_vector != NULL);
+    ASSERT_NE(src_vector, nullptr);
 
     rnd_.Reset(ACMRandom::DeterministicSeed());
   }
@@ -807,7 +807,7 @@
     rnd_.Reset(ACMRandom::DeterministicSeed());
     src_ = reinterpret_cast<CoeffType *>(
         aom_memalign(32, sizeof(*src_) * satd_size_));
-    ASSERT_TRUE(src_ != NULL);
+    ASSERT_NE(src_, nullptr);
   }
   virtual void TearDown() { aom_free(src_); }
   void FillConstant(const CoeffType val) {