Linux to posix conversion

Changed "linux" target to "posix". Most of the changes are shared with
QuRT and with OSX. The Linux specific parts are in for i2c which uses
<linux/i2c.h> and <linux/i2c-dev.h>.

There is also a check for __PX4_LINUX in mavlink for a tty ioctl that is
not supported.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Tools/posix_run.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+
+if [ ! -c /tmp/ttyS0 ] || [ ! -c /tmp/ttyS1 ]
+	then
+	echo "Need to create /tmp/ttyS[01]"
+	echo "socat PTY,link=/tmp/ttyS0 PTY,link=/tmp/ttyS1"
+	exit 1
+fi
+
+if [ ! -d /fs/msdcard ] && [ ! -w /fs/msdcard ]
+	then
+	echo "Need to create/mount writable /fs/microsd"
+	echo "sudo mkdir -p /fs/msdcard"
+	echo "sudo chmod 777 /fs/msdcard"
+	exit 1
+fi
+
+if [ ! -d /eeprom ] && [ ! -w /eeprom ]
+	then
+	echo "Need to create/mount writable /eeprom"
+	echo "sudo mkdir -p /eeprom"
+	echo "sudo chmod 777 /eeprom"
+	exit 1
+fi
+
+Build/linux_default.build/mainapp linux-configs/linuxtest/init/rc.S