Cleanup JDWP event matching

* Use std::vector for the event match list.
* Make event reporting methods void since result is never used.
* Use nullptr keyword instead of NULL.

Change-Id: Icd6f47e46cefc2cc63325df00037cd4b6a475259
diff --git a/runtime/jdwp/jdwp_expand_buf.cc b/runtime/jdwp/jdwp_expand_buf.cc
index 0a64f28..cc85cdd 100644
--- a/runtime/jdwp/jdwp_expand_buf.cc
+++ b/runtime/jdwp/jdwp_expand_buf.cc
@@ -57,7 +57,7 @@
  * Free a JdwpBuf and associated storage.
  */
 void expandBufFree(ExpandBuf* pBuf) {
-  if (pBuf == NULL) {
+  if (pBuf == nullptr) {
     return;
   }
 
@@ -93,7 +93,7 @@
   }
 
   uint8_t* newPtr = reinterpret_cast<uint8_t*>(realloc(pBuf->storage, pBuf->maxLen));
-  if (newPtr == NULL) {
+  if (newPtr == nullptr) {
     LOG(FATAL) << "realloc(" << pBuf->maxLen << ") failed";
   }