ART: Factor out native stack dumping

Move DumpNativeStack and DumpKernelStack into a new file to keep
concerns separated. Clean up the file.

In preparation for modifications to how we use addr2line.

Bug: 30351473
Test: m test-art-host
Test: manual host testing with a test that times out
Change-Id: I02d5645952fe94fd8e73bcf0522721547f6cef66
diff --git a/runtime/Android.mk b/runtime/Android.mk
index 9c813e2..7a37f60 100644
--- a/runtime/Android.mk
+++ b/runtime/Android.mk
@@ -132,6 +132,7 @@
   mirror/throwable.cc \
   monitor.cc \
   native_bridge_art_interface.cc \
+  native_stack_dump.cc \
   native/dalvik_system_DexFile.cc \
   native/dalvik_system_VMDebug.cc \
   native/dalvik_system_VMRuntime.cc \