Add support for the RTAI real-time extension

[Peter: fix rtai Config.in]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/rtai/Config.in

@@ -0,0 +1,7 @@
+config BR2_PACKAGE_RTAI
+	bool "rtai"
+	depends on BR2_LINUX_KERNEL_EXT_RTAI
+	help
+	  RTAI - the RealTime Application Interface for Linux.
+
+	  http://www.rtai.org

package/rtai/rtai.mk

@@ -0,0 +1,15 @@
+RTAI_VERSION = 3.8.1
+RTAI_SOURCE  = rtai-$(RTAI_VERSION).tar.bz2
+RTAI_SITE    = http://www.rtai.org/RTAI/
+
+RTAI_DEPENDENCIES = linux
+
+RTAI_CONF_OPT = \
+	--with-linux-dir=$(LINUX_DIR) 	\
+	--disable-leds		      	\
+	--disable-rtailab		\
+	--with-module-dir=/lib/modules/$(LINUX_VERSION_PROBED)/kernel/rtai
+
+RTAI_MAKE = $(MAKE1)
+
+$(eval $(call AUTOTARGETS,package,rtai))