Speed avifinfo_fuzz.cc up for large input strings

Change-Id: I169f874a673834db3ac32812bf3f2bb25d9ac851

tests/avifinfo_fuzz.cc

diff --git a/tests/avifinfo_fuzz.cc b/tests/avifinfo_fuzz.cc
index 670808e..c289ceb 100644
--- a/tests/avifinfo_fuzz.cc
+++ b/tests/avifinfo_fuzz.cc
@@ -66,8 +66,10 @@
   // for a given size and a status that is not kAvifInfoNotEnoughData, any
   // bigger size (of the same data) should return the same status and features.
   for (size_t size = 0; size < data_size; ++size) {
-    // Speed up considerably once it is highly likely the header is parsed.
-    if (size > 4096) size = std::min(data_size, size + 511);
+    if (size > 1024 || previous_status_features != kAvifInfoNotEnoughData) {
+      // The behavior is unlikely to change: save computing resources.
+      size = std::min(data_size, size * 2);
+    }
 
     // Simple raw pointer API.
     AvifInfoFeatures features;