skill, snice: do not encourage building these utilities

Both skill and snice are are mentioned in manual page to be 'obsolete
and unportable'.  This commit discourages distributors to keep these
commands part of default system.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

Makefile.am

@@ -25,8 +25,6 @@ usrbin_exec_PROGRAMS = \
 	pkill \
 	pmap \
 	pwdx \
-	skill \
-	snice \
 	tload \
 	uptime \
 	vmstat \
@@ -38,8 +36,6 @@ dist_man_MANS = \
 	pkill.1 \
 	pmap.1 \
 	pwdx.1 \
-	skill.1 \
-	snice.1 \
 	sysctl.8 \
 	sysctl.conf.5 \
 	tload.1 \
@@ -65,9 +61,18 @@ watch_SOURCES = watch.c $(top_srcdir)/lib/strutils.c
 watch_LDADD = @WATCH_NCURSES_LIBS@
 endif
 
-kill_SOURCES = skill.c $(top_srcdir)/lib/strutils.c
+if BUILD_SKILL
+usrbin_exec_PROGRAMS += \
+	skill \
+	snice
 skill_SOURCES = skill.c $(top_srcdir)/lib/strutils.c
 snice_SOURCES = skill.c $(top_srcdir)/lib/strutils.c
+dist_man_MANS += \
+	skill.1 \
+	snice.1
+endif
+
+kill_SOURCES = skill.c $(top_srcdir)/lib/strutils.c
 tload_SOURCES = tload.c $(top_srcdir)/lib/strutils.c
 pkill_SOURCES = pgrep.c
 free_SOURCES = free.c $(top_srcdir)/lib/strutils.c

configure.ac

@@ -179,6 +179,12 @@ AC_ARG_ENABLE([kill],
 AM_CONDITIONAL(BUILD_KILL, test "x$enable_kill" = xyes)
 AM_CONDITIONAL(LINUX, test "x$host_os" = xlinux-gnu)
 
+AC_ARG_ENABLE([skill],
+  AS_HELP_STRING([--enable-skill], [build skill and snice]),
+  [], enable_skill=no
+)
+AM_CONDITIONAL(BUILD_SKILL, test "x$build_skill" = xyes)
+
 AC_ARG_ENABLE([oomem],
   AS_HELP_STRING([--enable-oomem], [add out-of-memory fields to the library and top]),
   [], enable_oomem=no