[PATCH 02/16] tools lib bpf: Don't feature check when cleaning

[Wang Nan <wangnan0@huawei.com>]

Before this patch libbpf always do feature check even when cleaning.
For example:

 $ cd kernel/tools/lib/bpf
 $ make

 Auto-detecting system features:
 ...                        libelf: [ on  ]
 ...                           bpf: [ on  ]

   CC       libbpf.o
   CC       bpf.o
   LD       libbpf-in.o
   LINK     libbpf.a
   LINK     libbpf.so
 $ make clean
   CLEAN    libbpf
   CLEAN    core-gen
 $ make clean

 Auto-detecting system features:
 ...                        libelf: [ on  ]
 ...                           bpf: [ on  ]

   CLEAN    libbpf
   CLEAN    core-gen
 $

Although the first 'make clean' doesn't show feature check result,
it still does the check. No output because check result is similar
to FEATURE-DUMP.libbpf.

This patch uses same method as perf to turn off feature checking
when 'make clean'.

Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
---
 tools/lib/bpf/Makefile | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index a3caaf3..636e3dd 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -71,7 +71,17 @@ FEATURE_DISPLAY = libelf bpf
 INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/arch/$(ARCH)/include/uapi -I$(srctree)/include/uapi
 FEATURE_CHECK_CFLAGS-bpf = $(INCLUDES)
 
+check_feat := 1
+NON_CHECK_FEAT_TARGETS := clean TAGS tags cscope help
+ifdef MAKECMDGOALS
+ifeq ($(filter-out $(NON_CHECK_FEAT_TARGETS),$(MAKECMDGOALS)),)
+  check_feat := 0
+endif
+endif
+
+ifeq ($(check_feat),1)
 include $(srctree)/tools/build/Makefile.feature
+endif
 
 export prefix libdir src obj
 
-- 
1.8.3.4