atmel samd: Basic framework.

Thoughts: should this be a "sam0" family rather than samd?  (Much like Atmel's
own software package lumps all the cortex-m0+ devices in one family)

This was enough to get a basic blinky working at least.

lib/sam/d/Makefile

@@ -0,0 +1,38 @@
+##
+## This file is part of the libopencm3 project.
+##
+## Copyright (C) 2016 Karl Palsson <karlp@tweak.net.au>
+##
+## This library is free software: you can redistribute it and/or modify
+## it under the terms of the GNU Lesser General Public License as published by
+## the Free Software Foundation, either version 3 of the License, or
+## (at your option) any later version.
+##
+## This library is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU Lesser General Public License for more details.
+##
+## You should have received a copy of the GNU Lesser General Public License
+## along with this library.  If not, see <http://www.gnu.org/licenses/>.
+##
+
+LIBNAME		= libopencm3_samd
+SRCLIBDIR	?= ../..
+
+PREFIX		?= arm-none-eabi
+
+CC		= $(PREFIX)-gcc
+AR		= $(PREFIX)-ar
+TGT_CFLAGS	= -Os -Wall -Wextra -I../../../include -fno-common \
+		  -mcpu=cortex-m0plus -mthumb $(FP_FLAGS) -Wstrict-prototypes \
+		  -ffunction-sections -fdata-sections -MD -DSAMD
+TGT_CFLAGS      += $(DEBUG_FLAGS)
+# ARFLAGS	= rcsv
+ARFLAGS		= rcs
+OBJS		= 
+
+VPATH += ../../cm3:../common
+
+include ../../Makefile.include
+