Fix name clash with libcap 2.29.

Taken from upstream:
https://github.com/iputils/iputils/commit/18f9a84e0e702841d6cc4d5f593de4fbd1348e83

diff --git a/ninfod/ninfod.c b/ninfod/ninfod.c
--- a/ninfod/ninfod.c
+++ b/ninfod/ninfod.c
@@ -455,7 +455,7 @@ static void do_daemonize(void)
 /* --------- */
 #ifdef HAVE_LIBCAP
 static const cap_value_t cap_net_raw = CAP_NET_RAW;
-static const cap_value_t cap_setuid =  CAP_SETUID; 
+static const cap_value_t cap_setuserid = CAP_SETUID;
 static cap_flag_value_t cap_ok;
 #else
 static uid_t euid;
@@ -487,7 +487,7 @@ static void limit_capabilities(void)
 
 	cap_get_flag(cap_cur_p, CAP_SETUID, CAP_PERMITTED, &cap_ok);
 	if (cap_ok != CAP_CLEAR)
-		cap_set_flag(cap_p, CAP_PERMITTED, 1, &cap_setuid, CAP_SET);
+		cap_set_flag(cap_p, CAP_PERMITTED, 1, &cap_setuserid, CAP_SET);
 
 	if (cap_set_proc(cap_p) < 0) {
 		DEBUG(LOG_ERR, "cap_set_proc: %s\n", strerror(errno));
@@ -520,8 +520,8 @@ static void drop_capabilities(void)
 
 	/* setuid / setuid */
 	if (cap_ok != CAP_CLEAR) {
-		cap_set_flag(cap_p, CAP_PERMITTED, 1, &cap_setuid, CAP_SET);
-		cap_set_flag(cap_p, CAP_EFFECTIVE, 1, &cap_setuid, CAP_SET);
+		cap_set_flag(cap_p, CAP_PERMITTED, 1, &cap_setuserid, CAP_SET);
+		cap_set_flag(cap_p, CAP_EFFECTIVE, 1, &cap_setuserid, CAP_SET);
 
 		if (cap_set_proc(cap_p) < 0) {
 			DEBUG(LOG_ERR, "cap_set_proc: %s\n", strerror(errno));
0bd83acb39a0f8085d22d3813d'>commit</a><a href='/guix/diff/gnu/packages/hurd.scm?id=1b90e57eb75e760bd83acb39a0f8085d22d3813d'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/hurd.scm'>
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<div class='path'>path: <a href='/guix/log/?id=1b90e57eb75e760bd83acb39a0f8085d22d3813d'>root</a>/<a href='/guix/log/gnu?id=1b90e57eb75e760bd83acb39a0f8085d22d3813d'>gnu</a>/<a href='/guix/log/gnu/packages?id=1b90e57eb75e760bd83acb39a0f8085d22d3813d'>packages</a>/<a href='/guix/log/gnu/packages/hurd.scm?id=1b90e57eb75e760bd83acb39a0f8085d22d3813d'>hurd.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/hurd.scm?id=1b90e57eb75e760bd83acb39a0f8085d22d3813d&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2015-11-13 23:45:55 +0800'>2015-11-13</span></td><td><a href='/guix/commit/gnu/packages/hurd.scm?id=a124bbd2f41410e1c33654f4ff9865765baf28a7'>gnu: Adjust formatting as recommended by 'guix lint'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/aidc.scm (barcode, qrencode),
  gnu/packages/bash.scm (bash, bash-completion),
  gnu/packages/busybox.scm (busybox),
  gnu/packages/cdrom.scm (cdparanoia),
  gnu/packages/cmake.scm (cmake),
  gnu/packages/conkeror.scm (conkeror),
  gnu/packages/cook.scm (cook),
  gnu/packages/curl.scm (curl),
  gnu/packages/docbook.scm (docbook-xsl),
  gnu/packages/enlightenment.scm (enlightenment),
  gnu/packages/games.scm (abbaye),
  gnu/packages/geeqie.scm (exiv2),
  gnu/packages/gimp.scm (gegl),
  gnu/packages/gl.scm (glu, freeglut, ftgl),
  gnu/packages/glib.scm (glib),
  gnu/packages/gnome.scm (orbit2, gconf, geocode-glib),
  gnu/packages/gstreamer.scm (gstreamer, gst-plugins-base),
  gnu/packages/linux.scm (util-linux),
  gnu/packages/lisp.scm (gcl, ecl),
  gnu/packages/maths.scm (gnuplot, hdf5),
  gnu/packages/ssh.scm (dropbear),
  gnu/packages/web.scm (json-c): Remove tabulations and trailing
  white spaces or reformat to fit within 80 columns.
* gnu/packages/audio.scm (aubio),
  gnu/packages/emacs.scm (emacs-s),
  gnu/packages/engineering.scm (geda-gaf),
  gnu/packages/games.scm (dosbox),
  gnu/packages/gnome.scm (gusb),
  gnu/packages/gtk.scm (gtk+),
  gnu/packages/guile.scm (guile-wisp),
  gnu/packages/hurd.scm (hurd-headers),
  gnu/packages/wm.scm (i3-wm): Adjust synopsis or description.
</span></span></td><td>宋文武</td></tr>
<tr><td><span title='2015-11-01 15:48:32 +0200'>2015-11-01</span></td><td><a href='/guix/commit/gnu/packages/hurd.scm?id=67010dd886402d60c6cb2776b7c1b4655ac87986'>gnu: hurd-headers: Update to 0.7</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/hurd.scm (hurd-headers): Update to version 0.7.
</span></span></td><td>Manolis Ragkousis</td></tr>
<tr><td><span title='2015-11-01 15:48:32 +0200'>2015-11-01</span></td><td><a href='/guix/commit/gnu/packages/hurd.scm?id=212c664889d4a8bc0cfa3d5ac6bc4b4a2f8be327'>gnu: mig: Update to 1.6</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/hurd.scm (mig): Update to version 1.6.
</span></span></td><td>Manolis Ragkousis</td></tr>
<tr><td><span title='2015-11-01 15:48:32 +0200'>2015-11-01</span></td><td><a href='/guix/commit/gnu/packages/hurd.scm?id=c51525895aa6f9ae7a6d2cd67c023f7c875f6a4b'>gnu: gnumach-headers: Update to 1.6</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/hurd.scm (gnumach-headers): Update to version 1.6.
</span></span></td><td>Manolis Ragkousis</td></tr>