perf tests: Fix PYTHONPATH for python-use test tracepoints

If there's not OUTPUT variable defined the PYTHONPATH ends up with
/python. We need to remove the extra '/'.
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/n/tip-h1hzfyfcdxjnuq9fin2cjwlr@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Makefile

@@ -958,7 +958,7 @@ $(OUTPUT)tests/attr.o: tests/attr.c $(OUTPUT)PERF-CFLAGS
 
 $(OUTPUT)tests/python-use.o: tests/python-use.c $(OUTPUT)PERF-CFLAGS
 	$(QUIET_CC)$(CC) -o $@ -c $(ALL_CFLAGS) \
-		-DPYTHONPATH='"$(OUTPUT)/python"' \
+		-DPYTHONPATH='"$(OUTPUT)python"' \
 		-DPYTHON='"$(PYTHON_WORD)"' \
 		$<