tools/perf/build: Make sure autodep feature binaries honor the O= setting

Arnaldo noticed that the feature-check binaries are generated in the
config/check-features/ directory even if O= is specified.

Implement $(OUTPUT) logic for config/check-features/Makefile.

Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/n/tip-NLwlnv5prsubuey0vfocebym@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tools/perf/config/Makefile

@@ -88,9 +88,14 @@ CFLAGS += -std=gnu99
 
 EXTLIBS = -lelf -lpthread -lrt -lm -ldl
 
+ifneq ($(OUTPUT),)
+  OUTPUT_FEATURES = $(OUTPUT)config/feature-checks/
+  $(shell mkdir -p $(OUTPUT_FEATURES))
+endif
+
 feature_check = $(eval $(feature_check_code))
 define feature_check_code
-  feature-$(1) := $(shell $(MAKE) -C config/feature-checks test-$1 >/dev/null 2>/dev/null && echo 1 || echo 0)
+  feature-$(1) := $(shell $(MAKE) OUTPUT=$(OUTPUT_FEATURES) -C config/feature-checks test-$1 >/dev/null 2>/dev/null && echo 1 || echo 0)
 endef
 
 feature_set = $(eval $(feature_set_code))
@@ -138,7 +143,7 @@ CORE_FEATURE_TESTS =			\
 # to skip the print-out of the long features list if the file
 # existed before and after it was built:
 #
-ifeq ($(wildcard config/feature-checks/test-all),)
+ifeq ($(wildcard $(OUTPUT)config/feature-checks/test-all),)
   test-all-failed := 1
 else
   test-all-failed := 0
@@ -168,7 +173,7 @@ ifeq ($(feature-all), 1)
   #
   $(foreach feat,$(CORE_FEATURE_TESTS),$(call feature_set,$(feat)))
 else
-  $(shell $(MAKE) -i -j -C config/feature-checks $(CORE_FEATURE_TESTS) >/dev/null 2>&1)
+  $(shell $(MAKE) OUTPUT=$(OUTPUT_FEATURES) -i -j -C config/feature-checks $(CORE_FEATURE_TESTS) >/dev/null 2>&1)
   $(foreach feat,$(CORE_FEATURE_TESTS),$(call feature_check,$(feat)))
 endif