build: fix logname systemd linkage

Note there was worry about redundant linking with -lsystemd
when getlogin() is not replaced, however that is mitigated
in general with the --as-needed linker option (the lib-ignore
gnulib module). Tested with:

  ./configure --with-systemd gl_cv_func_getlogin_works=no

* NEWS: Mention the Build-related fix.
Reported at https://bugs.debian.org/1129960

NEWS

@@ -142,6 +142,9 @@ GNU coreutils NEWS                                    -*- outline -*-
 
 ** Build-related
 
+  'logname' now builds, where getlogin() is replaced (e.g. with musl),
+  and systemd libs are being used, by linking the required libraries.
+
   The multi-call binary built with configure --enable-single-binary is reduced
   in size by around 10KB through the more efficient reuse of the 'test' code
   by '[', and the 'true' code by 'false'.

src/local.mk

@@ -344,6 +344,7 @@ src_pinky_LDADD += $(READUTMP_LIB)
 src_uptime_LDADD += $(READUTMP_LIB)
 src_users_LDADD += $(READUTMP_LIB)
 src_who_LDADD += $(READUTMP_LIB)
+src_logname_LDADD += $(READUTMP_LIB)
 
 # for strsignal
 src_kill_LDADD += $(LIBTHREAD)