Building with LIBBPF_DYNAMIC still requires building libbpf as part of
bpftool, but the build also still accidentally builds it. Make the
parts of the build bringing in libbpf conditional. Don't build bpftool
is a bpftool exists from the which command.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/Makefile.perf | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 5438d1111f3b..296c00e224a0 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -960,10 +960,12 @@ $(LIBAPI)-clean:
 	$(call QUIET_CLEAN, libapi)
 	$(Q)$(RM) -r -- $(LIBAPI_OUTPUT)
 
+ifndef LIBBPF_DYNAMIC
 $(LIBBPF): FORCE | $(LIBBPF_OUTPUT)
 	$(Q)$(MAKE) -C $(LIBBPF_DIR) FEATURES_DUMP=$(FEATURE_DUMP_EXPORT) \
 		O= OUTPUT=$(LIBBPF_OUTPUT)/ DESTDIR=$(LIBBPF_DESTDIR) prefix= subdir= \
 		EXTRA_CFLAGS="-fPIC" $@ install_headers
+endif
 
 $(LIBBPF)-clean:
 	$(call QUIET_CLEAN, libbpf)
@@ -1183,7 +1185,11 @@ $(SKEL_TMP_OUT) $(LIBAPI_OUTPUT) $(LIBBPF_OUTPUT) $(LIBPERF_OUTPUT) $(LIBSUBCMD_
 	$(Q)$(MKDIR) -p $@
 
 ifeq ($(CONFIG_PERF_BPF_SKEL),y)
+BPFTOOL := $(shell which bpftool)
+ifeq ($(BPFTOOL),)
 BPFTOOL := $(SKEL_TMP_OUT)/bootstrap/bpftool
+BUILD_BPFTOOL := y
+endif
 # Get Clang's default includes on this system, as opposed to those seen by
 # '--target=bpf'. This fixes "missing" files on some architectures/distros,
 # such as asm/byteorder.h, asm/socket.h, asm/sockios.h, sys/cdefs.h etc.
@@ -1202,16 +1208,21 @@ endif
 
 CLANG_OPTIONS = -Wall
 CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG),$(CLANG_TARGET_ARCH))
-BPF_INCLUDE := -I$(SKEL_TMP_OUT)/.. -I$(LIBBPF_INCLUDE) $(CLANG_SYS_INCLUDES)
+BPF_INCLUDE := -I$(SKEL_TMP_OUT)/.. $(CLANG_SYS_INCLUDES)
+ifneq ($(LIBBPF_INCLUDE),)
+  BPF_INCLUDE += -I$(LIBBPF_INCLUDE)
+endif
 TOOLS_UAPI_INCLUDE := -I$(srctree)/tools/include/uapi
 
 ifneq ($(WERROR),0)
   CLANG_OPTIONS += -Werror
 endif
 
+ifneq ($(BUILD_BPFTOOL),)
 $(BPFTOOL): | $(SKEL_TMP_OUT)
 	$(Q)CFLAGS= $(MAKE) -C ../bpf/bpftool \
 		OUTPUT=$(SKEL_TMP_OUT)/ bootstrap
+endif
 
 # Paths to search for a kernel to generate vmlinux.h from.
 VMLINUX_BTF_ELF_PATHS ?= $(if $(O),$(O)/vmlinux)			\
-- 
2.49.0.906.g1f30a19c02-goog