[PATCH V3] tools/perf: Add includes for detected configs in Makefile.perf

[Athira Rajeev <atrajeev@linux.vnet.ibm.com>]

Makefile.perf uses "CONFIG_*" checks in the code. Example the config
for libtraceevent is used to set PYTHON_EXT_SRCS

	ifeq ($(CONFIG_LIBTRACEEVENT),y)
	  PYTHON_EXT_SRCS := $(shell grep -v ^\# util/python-ext-sources)
	else
	  PYTHON_EXT_SRCS := $(shell grep -v '^\#\|util/trace-event.c' util/python-ext-sources)
	endif

But this is not picking the value for CONFIG_LIBTRACEEVENT that is
set using the settings in Makefile.config. Include the file
".config-detected" so that make will use the system detected
configuration in the CONFIG checks. This will fix isues that
could arise when other "CONFIG_*" checks are added to Makefile.perf
in future as well.

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
---
Changelog:
v2 -> v3:
Added -include since in some cases make clean or make
will fail when config is not included and if config-detected
file is not present.

v1 -> v2:
Added $(OUTPUT) prefix to config-detected as pointed
out by Ian

 tools/perf/Makefile.perf | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 37af6df7b978..f6fdc2d5a92f 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -351,6 +351,9 @@ export PYTHON_EXTBUILD_LIB PYTHON_EXTBUILD_TMP
 
 python-clean := $(call QUIET_CLEAN, python) $(RM) -r $(PYTHON_EXTBUILD) $(OUTPUT)python/perf*.so
 
+# Use the detected configuration
+-include $(OUTPUT).config-detected
+
 ifeq ($(CONFIG_LIBTRACEEVENT),y)
   PYTHON_EXT_SRCS := $(shell grep -v ^\# util/python-ext-sources)
 else
-- 
2.31.1