Arm stack unwinder

Simplified stack unwinder for ARM. This is port of
http://www.mcternan.me.uk/ArmStackUnwinding/
backtrace() is called from UIE() on native targets
and from panicf() on both native and ARM RaaA.

Change-Id: I8e4b3c02490dd60b30aa372fe842d193b8929ce0

lib/unwarminder/unwarminder.make

@@ -0,0 +1,21 @@
+#             __________               __   ___.
+#   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+#   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+#   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+#   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+#                     \/            \/     \/    \/            \/
+#
+
+UNWARM_DIR = $(ROOTDIR)/lib/unwarminder
+UNWARM_SRC = $(call preprocess, $(UNWARM_DIR)/SOURCES)
+UNWARM_OBJ := $(call c2obj, $(UNWARM_SRC))
+
+OTHER_SRC += $(UNWARM_SRC)
+
+UNWARMINDER = $(BUILDDIR)/lib/libunwarminder.a
+
+INCLUDES += -I$(UNWARM_DIR)
+
+$(UNWARMINDER): $(UNWARM_OBJ)
+	$(SILENT)$(shell rm -f $@)
+	$(call PRINTS,AR $(@F))$(AR) rcs $@ $^ >/dev/null