zephyr: Move Zephyr build to top level

The Zephyr build system does strange things if it refers to source
directories above the main Makefile (generating
outdir/<target>/../boot/... paths).  For now, fix this by moving the
Zephyr Makefile to the top-level in the tree.  This shouldn't have much
impact on Mynewt, as it doesn't use makefiles.

.gitignore

@@ -0,0 +1,3 @@
+outdir/
+.*.swp
+target.sh

Makefile

@@ -1,4 +1,5 @@
 BOARD ?= qemu_x86
-CONF_FILE = prj.conf
+CONF_FILE = zephyr/prj.conf
+SOURCE_DIR = zephyr/src
 
 include ${ZEPHYR_BASE}/Makefile.inc

build_boot.sh

@@ -1,6 +1,6 @@
 #! /bin/bash
 
 source $(dirname 0)/target.sh
-source ../../zephyr/zephyr-env.sh
+source ../zephyr/zephyr-env.sh
 
 make BOARD=$BOARD "$@"

zephyr/src/Makefile

@@ -1,5 +1,5 @@
-subdir-ccflags-y += -I$(PROJECT)/../boot/bootutil/include
-subdir-ccflags-y += -I$(PROJECT)/include
+subdir-ccflags-y += -I$(PROJECT)/boot/bootutil/include
+subdir-ccflags-y += -I$(PROJECT)/zephyr/include
 
 obj-y += main.o
 obj-y += flash_map.o hal_flash.o os.o