Updates specfile to match distro guidelines. Suppots modifying client directory path at build time.

- Support relocating client files at build time (required for LSB compliant nodes)
- OS varable added to perform some make choices
- Saving and exporting the Makefile vars now scripted using list of variables
- Updated specfile to match RH and SUSE requirements and guidelines
- Moved /usr/local/var to /var/local; dynamic files shall not use /usr.
- State files use %sharedstatedir for path (std for SLE and RHEL)
- Release value adjusted to meet different DEB and RPM reqs.

Signed-off-by: jcsiadal <jeremy.c.siadal@intel.com>

overlays/wwinit/etc/systemd/system/wwclient.service.in

@@ -5,7 +5,7 @@ After=local-fs.target
 
 [Service]
 Type=notify
-ExecStart=/warewulf/bin/wwclient
+ExecStart=@WWCLIENTDIR@/wwclient
 ExecReload=/bin/kill -s SIGHUP "$MAINPID"
 PIDFile=/var/run/wwclient.pid
 TimeoutSec=60