src.opts.mk: Retire BSD_CPIO option

Prior to commit 6973701a00 ("1. Make the BSD version of cpio the
default [1]") GNU cpio was installed unconditionally.  The BSD_CPIO
option was added when we introduced the BSD licensed, libarchive-based
cpio, to support installation of GNU cpio, libarchive cpio, or both.

GNU cpio was removed long ago and there is no longer a need for this
option.  We can just install BSD cpio unconditionally.

Reviewed by:	des
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D55467

share/man/man5/src.conf.5

@@ -1,5 +1,5 @@
 .\" DO NOT EDIT-- this file is @generated by tools/build/options/makeman.
-.Dd February 13, 2026
+.Dd March 3, 2026
 .Dt SRC.CONF 5
 .Os
 .Sh NAME
@@ -296,9 +296,6 @@ Do not build
 .Xr bsdinstall 8 ,
 .Xr sade 8 ,
 and related programs.
-.It Va WITHOUT_BSD_CPIO
-Do not build the BSD licensed version of cpio based on
-.Xr libarchive 3 .
 .It Va WITHOUT_BSNMP
 Do not build or install
 .Xr bsnmpd 1

share/mk/src.opts.mk

@@ -71,7 +71,6 @@ __DEFAULT_YES_OPTIONS = \
     BOOT \
     BOOTPARAMD \
     BOOTPD \
-    BSD_CPIO \
     BSDINSTALL \
     BSNMP \
     BZIP2 \