fix uint32_t <-> size_t mismatch in tests

Change-Id: Ifde4d57957219560e01ebd1657f1c0721f041054

test/blend_a64_mask_1d_test.cc

diff --git a/test/blend_a64_mask_1d_test.cc b/test/blend_a64_mask_1d_test.cc
index 97608b8..4377e65 100644
--- a/test/blend_a64_mask_1d_test.cc
+++ b/test/blend_a64_mask_1d_test.cc
@@ -93,16 +93,16 @@
 
   T dst_ref_[kBufSize];
   T dst_tst_[kBufSize];
-  size_t dst_stride_;
-  size_t dst_offset_;
+  uint32_t dst_stride_;
+  uint32_t dst_offset_;
 
   T src0_[kBufSize];
-  size_t src0_stride_;
-  size_t src0_offset_;
+  uint32_t src0_stride_;
+  uint32_t src0_offset_;
 
   T src1_[kBufSize];
-  size_t src1_stride_;
-  size_t src1_offset_;
+  uint32_t src1_stride_;
+  uint32_t src1_offset_;
 
   uint8_t mask_[kMaxMaskSize];