perf tools: Disable parallelism for 'make clean'

BugLink: https://bugs.launchpad.net/bugs/1810807

[ Upstream commit da15fc2f ]

The Yocto build system does a 'make clean' when rebuilding due to
changed dependencies, and that consistently fails for me (causing the
whole BSP build to fail) with errors such as

| find: '[...]/perf/1.0-r9/perf-1.0/plugin_mac80211.so': No such file or directory
| find: '[...]/perf/1.0-r9/perf-1.0/plugin_mac80211.so': No such file or directory
| find: find: '[...]/perf/1.0-r9/perf-1.0/libtraceevent.a''[...]/perf/1.0-r9/perf-1.0/libtraceevent.a': No such file or directory: No such file or directory
|
[...]
| find: cannot delete '/mnt/xfs/devel/pil/yocto/tmp-glibc/work/wandboard-oe-linux-gnueabi/perf/1.0-r9/perf-1.0/util/.pstack.o.cmd': No such file or directory

Apparently (despite the comment), 'make clean' ends up launching
multiple sub-makes that all want to remove the same things - perhaps
this only happens in combination with a O=... parameter. In any case, we
don't lose much by explicitly disabling the parallelism for the clean
target, and it makes automated builds much more reliable.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180705131527.19749-1-linux@rasmusvillemoes.dkSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

tools/perf/Makefile

@@ -69,10 +69,10 @@ all tags TAGS:
 	$(make)
 
 #
-# The clean target is not really parallel, don't print the jobs info:
+# Explicitly disable parallelism for the clean target.
 #
 clean:
-	$(make)
+	$(make) -j1
 
 #
 # The build-test target is not really parallel, don't print the jobs info: