lz4diff: Check array bounds prior to access

Test: TreeHugger
Bug: 206729162
Change-Id: If8a5a2dfab7728246eba3a2b4ad7b7e1f52751e3
diff --git a/lz4diff/lz4diff_compress.cc b/lz4diff/lz4diff_compress.cc
index e580c91..67b02de 100644
--- a/lz4diff/lz4diff_compress.cc
+++ b/lz4diff/lz4diff_compress.cc
@@ -149,8 +149,8 @@
     }
     size_t inputmargin = 0;
     if (zero_padding_enabled) {
-      while (cluster[inputmargin] == 0 &&
-             inputmargin < std::min(kBlockSize, cluster.size())) {
+      while (inputmargin < std::min(kBlockSize, cluster.size()) &&
+             cluster[inputmargin] == 0) {
         inputmargin++;
       }
     }