fuzz_imagedecoder: ignore allocation failures

Bug: 142252770
Bug: 169137236
Bug: 169139756
Test: this

Image decoders may attempt to allocate a large amount of memory
(especially if the encoded image is large). This doesn't necessarily
mean there is a bug. Set allocator_may_return_null = 1 for hwasan so the
fuzzer can continue running.

Change-Id: Ib750a142e28d01144036409786e631dfb783283f
diff --git a/native/graphics/jni/Android.bp b/native/graphics/jni/Android.bp
index b9aefdd..3751564 100644
--- a/native/graphics/jni/Android.bp
+++ b/native/graphics/jni/Android.bp
@@ -89,6 +89,13 @@
         asan_options: [
             "detect_odr_violation=1",
         ],
+        hwasan_options: [
+             // Image decoders may attempt to allocate a large amount of memory
+             // (especially if the encoded image is large). This doesn't
+             // necessarily mean there is a bug. Set allocator_may_return_null=1
+             // for hwasan so the fuzzer can continue running.
+            "allocator_may_return_null = 1",
+        ],
     },
     corpus: ["corpus/*"],
     host_supported: true,