utils: Add ProcessCallStack to collect stack traces for all threads in a process

- Also add a Printer class (print lines to logcat, fd, or strings)

Bug: 11324229
Change-Id: I78435ed49aa196a0efb45bf9b2d58b62c41737d3
diff --git a/libutils/Android.mk b/libutils/Android.mk
index 7e6b1be..720443e 100644
--- a/libutils/Android.mk
+++ b/libutils/Android.mk
@@ -26,6 +26,8 @@
 	LinearAllocator.cpp \
 	LinearTransform.cpp \
 	Log.cpp \
+	Printer.cpp \
+	ProcessCallStack.cpp \
 	PropertyMap.cpp \
 	RefBase.cpp \
 	SharedBuffer.cpp \