perf python: Fix build when PYTHON_CONFIG is user supplied

stable inclusion
from stable-v5.10.140
commit 5a768c977085e75eaa7471fcefe65c01a7c1569c
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I63FTT

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5a768c977085e75eaa7471fcefe65c01a7c1569c

--------------------------------

commit bc9e7fe3 upstream.

The previous change to Python autodetection had a small mistake where
the auto value was used to determine the Python binary, rather than the
user supplied value. The Python binary is only used for one part of the
build process, rather than the final linking, so it was producing
correct builds in most scenarios, especially when the auto detected
value matched what the user wanted, or the system only had a valid set
of Pythons.

Change it so that the Python binary path is derived from either the
PYTHON_CONFIG value or PYTHON value, depending on what is specified by
the user. This was the original intention.

This error was spotted in a build failure an odd cross compilation
environment after commit 4c41cb46 ("perf python: Prefer
python3") was merged.

Fixes: 630af16e ("perf tools: Use Python devtools for version autodetection rather than runtime")
Signed-off-by: NJames Clark <james.clark@arm.com>
Acked-by: NIan Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220728093946.1337642-1-james.clark@arm.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>

tools/perf/Makefile.config

@@ -254,7 +254,7 @@ endif
 # defined. get-executable-or-default fails with an error if the first argument is supplied but
 # doesn't exist.
 override PYTHON_CONFIG := $(call get-executable-or-default,PYTHON_CONFIG,$(PYTHON_AUTO))
-override PYTHON := $(call get-executable-or-default,PYTHON,$(subst -config,,$(PYTHON_AUTO)))
+override PYTHON := $(call get-executable-or-default,PYTHON,$(subst -config,,$(PYTHON_CONFIG)))
 
 grep-libs  = $(filter -l%,$(1))
 strip-libs  = $(filter-out -l%,$(1))