tools: bpf: account for generated feature/ and libbpf/ directories

When building "tools/bpf" from the top of the Linux repository, the
build system passes a value for the $(OUTPUT) Makefile variable to
tools/bpf/Makefile and tools/bpf/bpftool/Makefile, which results in
generating "libbpf/" (for bpftool) and "feature/" (bpf and bpftool)
directories inside the tree.

This commit adds such directories to the relevant .gitignore files, and
edits the Makefiles to ensure they are removed on "make clean". The use
of "rm" is also made consistent throughout those Makefiles (relies on
the $(RM) variable, use "--" to prevent interpreting
$(OUTPUT)/$(DESTDIR) as options.

v2:
- New patch.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/bpf/.gitignore

 FEATURE-DUMP.bpf
+feature
 bpf_asm
 bpf_dbg
 bpf_exp.yacc.*

tools/bpf/Makefile

@@ -81,10 +81,11 @@ $(OUTPUT)bpf_exp.lex.o: $(OUTPUT)bpf_exp.lex.c
 
 clean: bpftool_clean
 	$(call QUIET_CLEAN, bpf-progs)
-	$(Q)rm -rf $(OUTPUT)*.o $(OUTPUT)bpf_jit_disasm $(OUTPUT)bpf_dbg \
+	$(Q)$(RM) -r -- $(OUTPUT)*.o $(OUTPUT)bpf_jit_disasm $(OUTPUT)bpf_dbg \
 	       $(OUTPUT)bpf_asm $(OUTPUT)bpf_exp.yacc.* $(OUTPUT)bpf_exp.lex.*
 	$(call QUIET_CLEAN, core-gen)
-	$(Q)rm -f $(OUTPUT)FEATURE-DUMP.bpf
+	$(Q)$(RM) -- $(OUTPUT)FEATURE-DUMP.bpf
+	$(Q)$(RM) -r -- $(OUTPUT)feature
 
 install: $(PROGS) bpftool_install
 	$(call QUIET_INSTALL, bpf_jit_disasm)

tools/bpf/bpftool/.gitignore

@@ -3,3 +3,5 @@
 bpftool*.8
 bpf-helpers.*
 FEATURE-DUMP.bpftool
+feature
+libbpf

tools/bpf/bpftool/Makefile

@@ -124,9 +124,11 @@ $(OUTPUT)%.o: %.c
 
 clean: $(LIBBPF)-clean
 	$(call QUIET_CLEAN, bpftool)
-	$(Q)$(RM) $(OUTPUT)bpftool $(OUTPUT)*.o $(OUTPUT)*.d
+	$(Q)$(RM) -- $(OUTPUT)bpftool $(OUTPUT)*.o $(OUTPUT)*.d
+	$(Q)$(RM) -r -- $(OUTPUT)libbpf/
 	$(call QUIET_CLEAN, core-gen)
-	$(Q)$(RM) $(OUTPUT)FEATURE-DUMP.bpftool
+	$(Q)$(RM) -- $(OUTPUT)FEATURE-DUMP.bpftool
+	$(Q)$(RM) -r -- $(OUTPUT)feature/
 
 install: $(OUTPUT)bpftool
 	$(call QUIET_INSTALL, bpftool)
@@ -137,8 +139,8 @@ install: $(OUTPUT)bpftool
 
 uninstall:
 	$(call QUIET_UNINST, bpftool)
-	$(Q)$(RM) $(DESTDIR)$(prefix)/sbin/bpftool
-	$(Q)$(RM) $(DESTDIR)$(bash_compdir)/bpftool
+	$(Q)$(RM) -- $(DESTDIR)$(prefix)/sbin/bpftool
+	$(Q)$(RM) -- $(DESTDIR)$(bash_compdir)/bpftool
 
 doc:
 	$(call descend,Documentation)