Merge branch 'Use lightweigt version of bpftool'

Pu Lehui says:

====================

Currently, samples/bpf, tools/runqslower and bpf/iterators use bpftool
for vmlinux.h, skeleton, and static linking only. We can use lightweight
bootstrap version of bpftool to handle these, and it will be faster.

v2:
- make libbpf and bootstrap bpftool independent. and make it simple.

v1: https://lore.kernel.org/bpf/20220712030813.865410-1-pulehui@huawei.com
====================
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

kernel/bpf/preload/iterators/Makefile

@@ -9,7 +9,7 @@ LLVM_STRIP ?= llvm-strip
 TOOLS_PATH := $(abspath ../../../../tools)
 BPFTOOL_SRC := $(TOOLS_PATH)/bpf/bpftool
 BPFTOOL_OUTPUT := $(abs_out)/bpftool
-DEFAULT_BPFTOOL := $(OUTPUT)/sbin/bpftool
+DEFAULT_BPFTOOL := $(BPFTOOL_OUTPUT)/bootstrap/bpftool
 BPFTOOL ?= $(DEFAULT_BPFTOOL)
 
 LIBBPF_SRC := $(TOOLS_PATH)/lib/bpf
@@ -61,9 +61,5 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
 		    OUTPUT=$(abspath $(dir $@))/ prefix=		       \
 		    DESTDIR=$(LIBBPF_DESTDIR) $(abspath $@) install_headers
 
-$(DEFAULT_BPFTOOL): $(BPFOBJ) | $(BPFTOOL_OUTPUT)
-	$(Q)$(MAKE) $(submake_extras) -C $(BPFTOOL_SRC)			       \
-		    OUTPUT=$(BPFTOOL_OUTPUT)/				       \
-		    LIBBPF_OUTPUT=$(LIBBPF_OUTPUT)/			       \
-		    LIBBPF_DESTDIR=$(LIBBPF_DESTDIR)/			       \
-		    prefix= DESTDIR=$(abs_out)/ install-bin
+$(DEFAULT_BPFTOOL): | $(BPFTOOL_OUTPUT)
+	$(Q)$(MAKE) $(submake_extras) -C $(BPFTOOL_SRC)	OUTPUT=$(BPFTOOL_OUTPUT)/ bootstrap

samples/bpf/Makefile

@@ -282,12 +282,10 @@ $(LIBBPF): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
 
 BPFTOOLDIR := $(TOOLS_PATH)/bpf/bpftool
 BPFTOOL_OUTPUT := $(abspath $(BPF_SAMPLES_PATH))/bpftool
-BPFTOOL := $(BPFTOOL_OUTPUT)/bpftool
-$(BPFTOOL): $(LIBBPF) $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) | $(BPFTOOL_OUTPUT)
-	    $(MAKE) -C $(BPFTOOLDIR) srctree=$(BPF_SAMPLES_PATH)/../../ \
-		OUTPUT=$(BPFTOOL_OUTPUT)/ \
-		LIBBPF_OUTPUT=$(LIBBPF_OUTPUT)/ \
-		LIBBPF_DESTDIR=$(LIBBPF_DESTDIR)/
+BPFTOOL := $(BPFTOOL_OUTPUT)/bootstrap/bpftool
+$(BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) | $(BPFTOOL_OUTPUT)
+	$(MAKE) -C $(BPFTOOLDIR) srctree=$(BPF_SAMPLES_PATH)/../../ 		\
+		OUTPUT=$(BPFTOOL_OUTPUT)/ bootstrap
 
 $(LIBBPF_OUTPUT) $(BPFTOOL_OUTPUT):
 	$(call msg,MKDIR,$@)

tools/bpf/runqslower/Makefile

@@ -4,7 +4,7 @@ include ../../scripts/Makefile.include
 OUTPUT ?= $(abspath .output)/
 
 BPFTOOL_OUTPUT := $(OUTPUT)bpftool/
-DEFAULT_BPFTOOL := $(BPFTOOL_OUTPUT)bpftool
+DEFAULT_BPFTOOL := $(BPFTOOL_OUTPUT)bootstrap/bpftool
 BPFTOOL ?= $(DEFAULT_BPFTOOL)
 LIBBPF_SRC := $(abspath ../../lib/bpf)
 BPFOBJ_OUTPUT := $(OUTPUT)libbpf/
@@ -86,6 +86,5 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(BPFOBJ_OU
 	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) OUTPUT=$(BPFOBJ_OUTPUT) \
 		    DESTDIR=$(BPFOBJ_OUTPUT) prefix= $(abspath $@) install_headers
 
-$(DEFAULT_BPFTOOL): $(BPFOBJ) | $(BPFTOOL_OUTPUT)
-	$(Q)$(MAKE) $(submake_extras) -C ../bpftool OUTPUT=$(BPFTOOL_OUTPUT)   \
-		    ARCH= CROSS_COMPILE= CC=$(HOSTCC) LD=$(HOSTLD)
+$(DEFAULT_BPFTOOL): | $(BPFTOOL_OUTPUT)
+	$(Q)$(MAKE) $(submake_extras) -C ../bpftool OUTPUT=$(BPFTOOL_OUTPUT) bootstrap