configure: Add --disable-w

Some systems implement utmp as a stub so it doesn't make sense to have
a non-functioning w.  This change mitigates #193 and !126

References:
 procps-ng/procps!129
 procps-ng/procps!126
 procps-ng/procps#193

Makefile.am

@@ -51,8 +51,7 @@ bin_PROGRAMS = \
 	pwdx \
 	tload \
 	uptime \
-	vmstat \
-	w
+	vmstat
 if BUILD_PIDWAIT
 bin_PROGRAMS += pidwait
 endif
@@ -64,8 +63,7 @@ usrbin_exec_PROGRAMS += \
 	pkill \
 	pmap \
 	uptime \
-	vmstat \
-	w
+	vmstat
 endif
 
 lib_LTLIBRARIES = \
@@ -78,7 +76,6 @@ dist_man_MANS = \
 	pmap.1 \
 	uptime.1 \
 	vmstat.8 \
-	w.1 \
 	doc/procps.3 \
 	doc/procps_pids.3 \
 	doc/procps_misc.3
@@ -144,6 +141,19 @@ else
   EXTRA_DIST += kill.1
 endif
 
+if BUILD_W
+if CYGWIN
+usrbin_exec_PROGRAMS += w
+else
+bin_PROGRAMS += w
+endif
+
+dist_man_MANS += w.1
+w_SOURCES = w.c lib/fileutils.c
+else
+  EXTRA_DIST += w.1
+endif
+
 if WITH_NCURSES
 if !CYGWIN
 bin_PROGRAMS += \
@@ -222,7 +232,6 @@ endif
 tload_SOURCES = tload.c lib/strutils.c lib/fileutils.c
 uptime_SOURCES = uptime.c lib/fileutils.c
 vmstat_SOURCES = vmstat.c lib/strutils.c lib/fileutils.c
-w_SOURCES = w.c lib/fileutils.c
 
 
 # See http://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html

configure.ac

@@ -243,6 +243,12 @@ AC_ARG_ENABLE([kill],
   [], [enable_kill=yes]
 )
 AM_CONDITIONAL(BUILD_KILL, test "x$enable_kill" = xyes)
+AC_ARG_ENABLE([w],
+  AS_HELP_STRING([--disable-w], [do not build w]),
+  [], [enable_w=yes]
+)
+AM_CONDITIONAL(BUILD_W, test "x$enable_w" = xyes)
+
 AM_CONDITIONAL(LINUX, test "x$host_os" = xlinux-gnu)
 AM_CONDITIONAL(CYGWIN, test "x$host_os" = xcygwin)