added linux bootstrap step & fixed case statement for the other builds

build/linux/build.bash

@@ -0,0 +1,43 @@
+. $PROJECTDIR/build/linux/package.env
+
+fetch $LINUX_URL
+
+cd $SOURCES && tar xf linux-$LINUX_VERSION.tar.xz && cd linux-$LINUX_VERSION
+
+make mrproper
+
+bootstrap() {
+    make headers
+    find usr/include -type f ! -name '*.h' -delete
+    cp -r usr/include $SYSROOT/usr
+}
+
+toolchain() {
+	echo toolchain
+}
+
+setup() {
+	echo setup
+}
+
+final() {
+	echo final
+}
+
+case $1 in 
+    bootstrap)
+		bootstrap
+		;;
+	toolchain)
+		toolchain
+		;;
+	setup)
+		setup
+		;;
+	final)
+		final
+		;;
+esac
+
+
+cd $SOURCES && rm -rf $SOURCES/linux-$LINUX_VERSION