sbin: build ping if at least one of INET & INET6 is enabled

It does not build (and serves no purpose) if neither is true (i.e.,
building WITHOUT_INET and WITHOUT_INET6).  Also add an explicit error
in ping to make this case clear.

PR:		260082
Sponsored by:	The FreeBSD Foundation

(cherry picked from commit a4ef9e58bc)

OptionalObsoleteFiles: remove ping with INET & INET6 disabled

Reported by:	kevans
Fixes:		a4ef9e58bc ("sbin: build ping if at least one of...")
Sponsored by:	The FreeBSD Foundation

(cherry picked from commit 0179739a00)

sbin/Makefile

@@ -53,7 +53,6 @@ SUBDIR=adjkerntz \
 	nfsiod \
 	nos-tun \
 	pfilctl \
-	ping \
 	rcorder \
 	reboot \
 	recoverdisk \
@@ -69,6 +68,10 @@ SUBDIR=adjkerntz \
 	tunefs \
 	umount
 
+.if ${MK_INET} != "no" || ${MK_INET6} != "no"
+SUBDIR+=	ping
+.endif
+
 SUBDIR.${MK_CCD}+=	ccdconfig
 SUBDIR.${MK_CXX}+=	devd
 SUBDIR.${MK_HAST}+=	hastctl

sbin/ping/main.c

@@ -57,6 +57,8 @@ __FBSDID("$FreeBSD$");
 #define	OPTSTR PING4OPTS
 #elif defined(INET6)
 #define	OPTSTR PING6OPTS
+#else
+#error At least one of INET and INET6 is required
 #endif
 
 int

tools/build/mk/OptionalObsoleteFiles.inc

@@ -2571,6 +2571,11 @@ OLD_DIRS+=usr/share/i18n/csmapper/KS
 OLD_DIRS+=usr/share/i18n/csmapper/GB
 .endif
 
+.if ${MK_INET} == no && ${MK_INET6} == no
+OLD_FILES+=sbin/ping
+OLD_FILES+=usr/share/man/man8/ping.8.gz
+.endif
+
 .if ${MK_INET6} == no
 OLD_FILES+=sbin/ping6
 OLD_FILES+=sbin/rtsol