Move ELF feature note tool to usr.bin/elfctl

elfctl is a tool for modifying the NT_FREEBSD_FEATURE_CTL ELF note,
which contains a set of flags for enabling or disabling vulnerability
mitigations and other features.

Reviewed by:	csjp, kib
MFC after:	2 weeks
Relnotes:	Yes
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D23910

usr.bin/Makefile

@@ -31,6 +31,7 @@ SUBDIR=	alias \
 	diff \
 	dirname \
 	du \
+	elfctl \
 	elfdump \
 	enigma \
 	env \

usr.bin/elfctl/Makefile

@@ -2,13 +2,10 @@
 
 ELFTCDIR=	${SRCTOP}/contrib/elftoolchain
 
-PROG=	controlelf
-SRCS=	controlelf.c
+PROG=	elfctl
 
 LIBADD=	elftc elf
 
 CFLAGS+=-I${ELFTCDIR}/libelftc -I${ELFTCDIR}/common
 
-WARNS?=	6
-
 .include <bsd.prog.mk>

usr.bin/elfctl/elfctl.1

@@ -26,11 +26,11 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 27, 2019
-.Dt CONTROLELF 1
+.Dd March 1, 2020
+.Dt ELFCTL 1
 .Os
 .Sh NAME
-.Nm controlelf
+.Nm elfctl
 .Nd change an ELF binary's feature control note
 .Sh SYNOPSIS
 .Nm
@@ -79,8 +79,8 @@ of the
 .Nm
 command:
 .Bd -literal -offset indent
-controlelf file
-controlelf -e +aslr file
+elfctl file
+elfctl -e +aslr file
 .Ed
 .Sh HISTORY
 .Nm