configure: don't build libutils if not needed

configure.ac

@@ -117,6 +117,8 @@ AC_ARG_ENABLE([documentation],
     AS_HELP_STRING([--disable-documentation], [Don't build Knot DNS documentation]), [], [enable_documentation=yes])
 AM_CONDITIONAL([HAVE_DOCS], [test "$enable_documentation" = "yes"])
 
+AM_CONDITIONAL([HAVE_LIBUTILS], test "$enable_utilities" != "no" -o \
+                                     "$enable_daemon" != "no")
 ######################
 # Generic dependencies
 ######################

src/utils/Makefile.inc

+if HAVE_LIBUTILS
 noinst_LTLIBRARIES += libknotus.la
 
 libknotus_la_CPPFLAGS = $(AM_CPPFLAGS) $(CFLAG_VISIBILITY) $(libidn2_LIBS) \
@@ -29,6 +30,7 @@ libknotus_la_SOURCES = \
 	utils/common/tls.h			\
 	utils/common/token.c			\
 	utils/common/token.h
+endif HAVE_LIBUTILS
 
 if HAVE_UTILS
 bin_PROGRAMS = kdig khost knsec3hash knsupdate