libhydra: Remove empty unused library

src/libcharon/Makefile.am

@@ -146,7 +146,6 @@ daemon.lo :		$(top_builddir)/config.status
 AM_CPPFLAGS = \
 	-I${linux_headers} \
 	-I$(top_srcdir)/src/libstrongswan \
-	-I$(top_srcdir)/src/libhydra \
 	-I$(top_srcdir)/src/libcharon \
 	-DIPSEC_DIR=\"${ipsecdir}\" \
 	-DIPSEC_PIDDIR=\"${piddir}\"
@@ -156,7 +155,6 @@ AM_LDFLAGS = \
 
 libcharon_la_LIBADD = \
   $(top_builddir)/src/libstrongswan/libstrongswan.la \
-  $(top_builddir)/src/libhydra/libhydra.la \
   -lm $(PTHREADLIB) $(DLLIB) $(SOCKLIB)
 
 if USE_WINDOWS