art: Disable debug tracing on production builds

When opening and closing activities in Settings, a significant amount of
CPU time is spent checking whether ATrace tags are enabled, as measured
by simpleperf:

0.12%     /system/lib64/libcutils.so                                                                                                                atrace_get_enabled_tag

ART debug tracing (via PALette) is responsible for a significant
portion of the time spent in the checks:

0.10%     0.07%  /system/lib64/libcutils.so                                                                                              atrace_get_enabled_tags
       |
       -- atrace_get_enabled_tags
          |
          |--30.47%-- PaletteTraceEnabled
          |    |
          |    |--96.11%-- art::Monitor::TryLock(art::Thread*, bool)
          |    |           void art::Monitor::Lock<(art::LockReason)1>(art::Thread*)
          |    |           art::Monitor::MonitorEnter(art::Thread*, art::ObjPtr<art::mirror::Object>, bool)
          |    |           artLockObjectFromCode
          |    |           art_quick_lock_object_no_inline
          |    |    |--8.63%-- [hit in function]
          |    |    |
          |    |    |--18.62%-- android.os.Parcel.obtain
          |
          |--2.44%-- PaletteTraceIntegerValue
          |    |
          |    |--25.86%-- art::mirror::String::AllocFromModifiedUtf8(art::Thread*, int, char const*, int)
          |    |
          |    |--22.90%-- art::mirror::Object* art::gc::Heap::AllocLargeObject<false, art::mirror::SetLengthVisitor>(art::Thread*, art::ObjPtr<art::mirror::Class>*, unsigned long, art::mirror::SetLengthVisitor const&)
          |    |
          |    |--19.85%-- artAllocArrayFromCodeResolvedRegionTLAB
          |    |
          |    |--19.71%-- art::mirror::String::AllocFromUtf16(art::Thread*, int, unsigned short const*)
          |    |
          |     --11.70%-- art::mirror::Object::Clone(art::Handle<art::mirror::Object>, art::Thread*)

We aren't going to use ATrace for ART in production systems, so disable
debug tracing in non-debug builds.

Test: simpleperf record -a; verify that PaletteTraceEnabled no longer
      appears under atrace_get_enabled_tags
Change-Id: If5cdb18adb17b04f5f7eb7c59cfb3f9ceaecb5be

Author: kdrag0n

libartbase/base/systrace.h

@@ -27,24 +27,37 @@
 namespace art {
 
 inline bool ATraceEnabled() {
+#ifdef NDEBUG
+  return false;
+#else
   bool enabled = false;
   if (UNLIKELY(PaletteTraceEnabled(&enabled) == PALETTE_STATUS_OK && enabled)) {
     return true;
   } else {
     return false;
   }
+#endif
 }
 
 inline void ATraceBegin(const char* name) {
+  (void)name;
+#ifndef NDEBUG
   PaletteTraceBegin(name);
+#endif
 }
 
 inline void ATraceEnd() {
+#ifndef NDEBUG
   PaletteTraceEnd();
+#endif
 }
 
 inline void ATraceIntegerValue(const char* name, int32_t value) {
+  (void)name;
+  (void)value;
+#ifndef NDEBUG
   PaletteTraceIntegerValue(name, value);
+#endif
 }
 
 class ScopedTrace {