Add more systracing everywhere

Added to:
JIT
DexFile functions
Oat file manager

Added helper ScopedTrace to prevent errors and reduce excess code.

Bug: 27502458

(cherry picked from commit dabdc0fe183d4684f3cf4d70cb09d318cff81b42)

Change-Id: Ifaeff8913d79eefc797380987d13cc00456266f8
diff --git a/runtime/base/arena_allocator.cc b/runtime/base/arena_allocator.cc
index 44af3f7..f871543 100644
--- a/runtime/base/arena_allocator.cc
+++ b/runtime/base/arena_allocator.cc
@@ -23,6 +23,7 @@
 #include "mem_map.h"
 #include "mutex.h"
 #include "thread-inl.h"
+#include "systrace.h"
 
 namespace art {
 
@@ -261,6 +262,7 @@
 
 void ArenaPool::TrimMaps() {
   if (!use_malloc_) {
+    ScopedTrace trace(__PRETTY_FUNCTION__);
     // Doesn't work for malloc.
     MutexLock lock(Thread::Current(), lock_);
     for (auto* arena = free_arenas_; arena != nullptr; arena = arena->next_) {