Added plugin stub of certexpire plugin

src/libcharon/plugins/certexpire/Makefile.am

@@ -0,0 +1,16 @@
+
+INCLUDES = -I$(top_srcdir)/src/libstrongswan -I$(top_srcdir)/src/libhydra \
+	-I$(top_srcdir)/src/libcharon
+
+AM_CFLAGS = -rdynamic \
+	-DIPSEC_PIDDIR=\"${piddir}\"
+
+if MONOLITHIC
+noinst_LTLIBRARIES = libstrongswan-certexpire.la
+else
+plugin_LTLIBRARIES = libstrongswan-certexpire.la
+endif
+
+libstrongswan_certexpire_la_SOURCES = certexpire_plugin.h certexpire_plugin.c
+
+libstrongswan_certexpire_la_LDFLAGS = -module -avoid-version