[monitoring-plugins] Include maxfd.h in lib Makefile

[RincewindsHat]

 Module: monitoring-plugins
 Branch: master
 Commit: 392ee835eeb66f41cb74fc57305ee17adae0fdae
 Author: RincewindsHat <12514511+RincewindsHat at users.noreply.github.com>
   Date: Wed Oct 18 10:30:18 2023 +0200
    URL: https://www.monitoring-plugins.org/repositories/monitoring-plugins/commit/?id=392ee83

Include maxfd.h in lib Makefile

This fixes a regression which was introduced with 719e27ddc2f0b48bcd7fe5584b23e3ce83ddf291
It prevents the creation of working release tarballs with the
current toolchain.

This commit add the header file maxfd.h to list of needed files.

---

 lib/Makefile.am | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/Makefile.am b/lib/Makefile.am
index 1a47395..dc3ee89 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -8,7 +8,7 @@ AM_CPPFLAGS = -DNP_STATE_DIR_PREFIX=\"$(localstatedir)\" \
 	-I$(srcdir) -I$(top_srcdir)/gl -I$(top_srcdir)/intl -I$(top_srcdir)/plugins
 
 libmonitoringplug_a_SOURCES = utils_base.c utils_disk.c utils_tcp.c utils_cmd.c maxfd.c
-EXTRA_DIST = utils_base.h utils_disk.h utils_tcp.h utils_cmd.h parse_ini.h extra_opts.h
+EXTRA_DIST = utils_base.h utils_disk.h utils_tcp.h utils_cmd.h parse_ini.h extra_opts.h maxfd.h
 
 if USE_PARSE_INI
 libmonitoringplug_a_SOURCES += parse_ini.c extra_opts.c