Autoconf 2.72 seems to be under preparation upstream, I therefore started to build dependent components to verify that they can be built once it lands in Fedora.

Your component fails to build with the new version of autoconf, due to the following error:

---
checking for ASYNCNS... yes
./configure: line 14202: syntax error near unexpected token `;;'
./configure: line 14202: `	 ;;'
error: Bad exit status from /var/tmp/rpm-tmp.71Mnpk (%build)
RPM build errors:
    Bad exit status from /var/tmp/rpm-tmp.71Mnpk (%build)
Child return code was: 1
---

The error is due to under-quoting of AS_IF parameters in configure.ac.

The proposed patch is the following:

---
diff -U5 -r netresolve-0.0.1/configure.ac netresolve-0.0.1.old/configure.ac
--- netresolve-0.0.1/configure.ac	2022-11-22 14:15:28.837157563 +0100
+++ netresolve-0.0.1.old/configure.ac	2022-11-22 13:47:43.692292809 +0100
@@ -59,13 +59,13 @@
 AM_CONDITIONAL(BUILD_FRONTEND_ASYNCNS, [test $build_asyncns = yes])
 AM_CONDITIONAL(BUILD_BACKEND_ASYNCNS, [test $build_asyncns = yes])
 
 AC_ARG_ENABLE(tests, AS_HELP_STRING([--enable-tests|--disable-tests], [Build tests using additional dependencies (Default: no)]))
 AS_IF([test "$enable_tests" = yes],
-	PKG_CHECK_MODULES([GLIB], [glib-2.0])
+	[PKG_CHECK_MODULES([GLIB], [glib-2.0])
 	AC_CHECK_LIB([event], [event_base_new], [EVENT_LIBS=-levent])
-	AC_SUBST(EVENT_LIBS))
+	AC_SUBST(EVENT_LIBS)])
 AM_CONDITIONAL(BUILD_ALL_TESTS, [test "$enable_tests" = yes])
 
 AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_FILES([
 	Makefile
---

Please have a look and get the problem fixed upstream.