Fix parallelizability in ApmTests.

Using temporary filenames instead of fixed ones permits them to run in
parallel.

BUG=chromium:445880
R=andrew@webrtc.org, kjellander@webrtc.org
TEST=third_party/gtest-parallel/gtest-parallel -r100 -w100 out-asan/out/Debug/modules_unittests --gtest_filter=*ApmTest*:*CommonFormats*

Review URL: https://webrtc-codereview.appspot.com/35709004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@8041 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed