Always clean on Android
Always clean on Android

Since we have to clean and rebuild for linux to get skdiff, the two platforms
were getting mixed up when the initial clean was skipped.

Unreviewed.

git-svn-id: 32fc27f4dcfb6c0385cd9719852b95fe6680452d@6196 2bbb7eff-a529-9590-31e7-b0007b416f81

Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot