perf tools: Ignore .config-detected in .gitignore

Commit fcfd6611 ("tools build: Add
detected config support") dynamically creates .config-detected. Add it
to .gitignore.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/1434542358-5430-1-git-send-email-wangnan0@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/.gitignore

@@ -28,3 +28,4 @@ config.mak.autogen
 *-flex.*
 *.pyc
 *.pyo
+.config-detected