perf: disable PARALLEL_MAKE

Autobuilder builds periodically and now more frequently have been
failing because of a race between the perf build and the newly
separated libtraceevent - perf tries to link libtraceevent.a, which
hasn't finished building yet in those cases.

This disables the parallel build to prevent that.

(From OE-Core rev: cd1e98513016c01e32bdb175ec7225d7378d952c)

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-kernel/perf/perf_3.4.bb

@@ -86,6 +86,8 @@ EXTRA_OEMAKE += "\
 	'infodir=${@oe.path.relative(prefix, infodir)}' \
 "
 
+PARALLEL_MAKE = ""
+
 do_compile() {
 	oe_runmake all
 }