Add support for disabling the Netlink plugin

Some vendors provide their own Netlink plugin to Finit.  This patch
makes it possible to disable the default netlink plugin from being
built.  However, even before this patch it was possible to overload
the plugin.  This just discards it from being built.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

plugins/Makefile.am

@@ -5,8 +5,7 @@ AM_CPPFLAGS        += -DFINIT_FIFO=\"$(fifo)\" $(lite_CFLAGS)
 
 if STATIC
 noinst_LTLIBRARIES  = libplug.la
-libplug_la_SOURCES  = bootmisc.c hwclock.c initctl.c netlink.c pidfile.c	\
-		      tty.c urandom.c
+libplug_la_SOURCES  = bootmisc.c hwclock.c initctl.c pidfile.c tty.c urandom.c
 
 if BUILD_ALSA_UTILS_PLUGIN
 libplug_la_SOURCES += alsa-utils.c
@@ -28,13 +27,16 @@ if BUILD_LOST_PLUGIN
 libplug_la_SOURCES += lost.c
 endif
 
+if BUILD_NETLINK_PLUGIN
+libplug_la_SOURCES += netlink.c
+endif
+
 if BUILD_RESOLVCONF_PLUGIN
 libplug_la_SOURCES += resolvconf.c
 endif
 
 else
-pkglib_LTLIBRARIES  = bootmisc.la hwclock.la initctl.la netlink.la pidfile.la	\
-		      tty.la urandom.la
+pkglib_LTLIBRARIES  = bootmisc.la hwclock.la initctl.la pidfile.la tty.la urandom.la
 
 if BUILD_ALSA_UTILS_PLUGIN
 pkglib_LTLIBRARIES += alsa-utils.la
@@ -56,6 +58,10 @@ if BUILD_LOST_PLUGIN
 pkglib_LTLIBRARIES += lost.la
 endif
 
+if BUILD_NETLINK_PLUGIN
+pkglib_LTLIBRARIES += netlink.la
+endif
+
 if BUILD_RESOLVCONF_PLUGIN
 pkglib_LTLIBRARIES += resolvconf.la
 endif