tools: bpftool: unify installation directories

Programs and documentation not managed by package manager are generally
installed under /usr/local/, instead of the user's home directory. In
particular, `man` is generally able to find manual pages under
`/usr/local/share/man`.

bpftool generally follows perf's example, and perf installs to home
directory. However bpftool requires root credentials, so it seems
sensible to follow the more common convention of installing files under
/usr/local instead. So, make /usr/local the default prefix for
installing the binary with `make install`, and the documentation with
`make doc-install`. Also, create /usr/local/sbin if it does not exist.

Note that the bash-completion file, however, is still installed under
/usr/share/bash-completion/completions, as the default setup for bash
does not attempt to load completion files under /usr/local/.
Reported-by: David Beckett <david.beckett@netronome.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/bpf/bpftool/Documentation/Makefile

@@ -6,7 +6,7 @@ RM ?= rm -f
 
 # Make the path relative to DESTDIR, not prefix
 ifndef DESTDIR
-prefix?=$(HOME)
+prefix ?= /usr/local
 endif
 mandir ?= $(prefix)/share/man
 man8dir = $(mandir)/man8

tools/bpf/bpftool/Makefile

@@ -45,8 +45,8 @@ $(LIBBPF)-clean:
 	$(call QUIET_CLEAN, libbpf)
 	$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(OUTPUT) clean >/dev/null
 
-prefix = /usr
-bash_compdir ?= $(prefix)/share/bash-completion/completions
+prefix = /usr/local
+bash_compdir ?= /usr/share/bash-completion/completions
 
 CC = gcc
 
@@ -76,6 +76,7 @@ clean: $(LIBBPF)-clean
 	$(Q)rm -rf $(OUTPUT)bpftool $(OUTPUT)*.o $(OUTPUT)*.d
 
 install:
+	install -m 0755 -d $(prefix)/sbin
 	install $(OUTPUT)bpftool $(prefix)/sbin/bpftool
 	install -m 0755 -d $(bash_compdir)
 	install -m 0644 bash-completion/bpftool $(bash_compdir)