Use iterators "before" the use node in HUserRecord<>.

Create a new template class IntrusiveForwardList<> that
mimicks std::forward_list<> except that all allocations
are handled externally. This is essentially the same as
boost::intrusive::slist<> but since we're not using Boost
we have to reinvent the wheel.

Use the new container to replace the HUseList and use the
iterators to "before" use nodes in HUserRecord<> to avoid
the extra pointer to the previous node which was used
exclusively for removing nodes from the list. This reduces
the size of the HUseListNode by 25%, 32B to 24B in 64-bit
compiler, 16B to 12B in 32-bit compiler. This translates
directly to overall memory savings for the 64-bit compiler
but due to rounding up of the arena allocations to 8B, we
do not get any improvement in the 32-bit compiler.

Compiling the Nexus 5 boot image with the 64-bit dex2oat
on host this CL reduces the memory used for compiling the
most hungry method, BatteryStats.dumpLocked(), by ~3.3MiB:

Before:
  MEM: used: 47829200, allocated: 48769120, lost: 939920
  Number of arenas allocated: 345,
  Number of allocations: 815492, avg size: 58
  ...
  UseListNode    13744640
  ...
After:
  MEM: used: 44393040, allocated: 45361248, lost: 968208
  Number of arenas allocated: 319,
  Number of allocations: 815492, avg size: 54
  ...
  UseListNode    10308480
  ...

Note that while we do not ship the 64-bit dex2oat to the
device, the JIT compilation for 64-bit processes is using
the 64-bit libart-compiler.

Bug: 28173563
Change-Id: I985eabd4816f845372d8aaa825a1489cf9569208
diff --git a/runtime/jni_internal_test.cc b/runtime/jni_internal_test.cc
index c718466..04ba8df 100644
--- a/runtime/jni_internal_test.cc
+++ b/runtime/jni_internal_test.cc
@@ -2286,16 +2286,16 @@
 // Test the offset computation of JNIEnvExt offsets. b/26071368.
 TEST_F(JniInternalTest, JNIEnvExtOffsets) {
   EXPECT_EQ(OFFSETOF_MEMBER(JNIEnvExt, local_ref_cookie),
-            JNIEnvExt::LocalRefCookieOffset(sizeof(void*)).Int32Value());
+            JNIEnvExt::LocalRefCookieOffset(sizeof(void*)).Uint32Value());
 
-  EXPECT_EQ(OFFSETOF_MEMBER(JNIEnvExt, self), JNIEnvExt::SelfOffset(sizeof(void*)).Int32Value());
+  EXPECT_EQ(OFFSETOF_MEMBER(JNIEnvExt, self), JNIEnvExt::SelfOffset(sizeof(void*)).Uint32Value());
 
   // segment_state_ is private in the IndirectReferenceTable. So this test isn't as good as we'd
   // hope it to be.
-  int32_t segment_state_now =
+  uint32_t segment_state_now =
       OFFSETOF_MEMBER(JNIEnvExt, locals) +
-      IndirectReferenceTable::SegmentStateOffset(sizeof(void*)).Int32Value();
-  int32_t segment_state_computed = JNIEnvExt::SegmentStateOffset(sizeof(void*)).Int32Value();
+      IndirectReferenceTable::SegmentStateOffset(sizeof(void*)).Uint32Value();
+  uint32_t segment_state_computed = JNIEnvExt::SegmentStateOffset(sizeof(void*)).Uint32Value();
   EXPECT_EQ(segment_state_now, segment_state_computed);
 }