Clean up JVMTI DDMS extension function.

We change it to not return failure (and print a warning) if the chunk
handler returns an empty chunk. This is a surprisingly common result
in real-world code and was causing significant log-spam.

Bug: 70559172
Test: ./test.py --host -j50
Change-Id: I1ba0f43cb2e834b09f51db75ec9100d97e916b62
diff --git a/openjdkjvmti/ti_extension.cc b/openjdkjvmti/ti_extension.cc
index afd0723..79a8cd6 100644
--- a/openjdkjvmti/ti_extension.cc
+++ b/openjdkjvmti/ti_extension.cc
@@ -216,7 +216,7 @@
       {
         { "type_in", JVMTI_KIND_IN, JVMTI_TYPE_JINT, false },
         { "length_in", JVMTI_KIND_IN, JVMTI_TYPE_JINT, false },
-        { "data_in", JVMTI_KIND_IN_BUF, JVMTI_TYPE_JBYTE, false },
+        { "data_in", JVMTI_KIND_IN_BUF, JVMTI_TYPE_JBYTE, true },
         { "type_out", JVMTI_KIND_OUT, JVMTI_TYPE_JINT, false },
         { "data_len_out", JVMTI_KIND_OUT, JVMTI_TYPE_JINT, false },
         { "data_out", JVMTI_KIND_ALLOC_BUF, JVMTI_TYPE_JBYTE, false }