projects-dir.mk: Add install-prereq-build

Add a target to pull in all prerequisites needed for building via the
package manager.

Signed-off-by: Jan Lindemann <jan@janware.com>

scripts/pkg-manager.sh

@@ -0,0 +1,53 @@
+#!/bin/sh
+
+log()
+{
+	echo $@ >&2
+}
+
+err()
+{
+	echo $@ >&2
+}
+
+fatal()
+{
+	err "Giving up: $@"
+	exit 1
+}
+
+usage()
+{
+	cat<<-EOT
+	$myname cmd args
+	EOT
+}
+
+run()
+{
+	log "Running ==== $@"
+	eval sudo "$@"
+}
+
+cmd_install()
+{
+	case $ID in
+	opensuse|suse)
+		eval run zypper in "$@"
+		;;
+	debian)
+		eval run apt-get install "$@"
+		;;
+	*)
+		fatal "Tried to install to unsupported platform \"$ID\""
+		;;
+	esac
+}
+
+# -- here we go
+myname=`basename $0`
+. /etc/os-release
+cmd="$1"
+shift
+eval cmd_$cmd "$@"
+