Bug 1006248. Part 1: Add MOZ_EXPORT in various places. r=glandium

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extra : rebase_source : cfe209a412cae28d405eae413415cebb6959072a
Bug 1006248. Part 2: Add NO_VISIBILITY_FLAGS to media/omx-plugin. r=glandium

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extra : rebase_source : eb5bc3174be7ee20d4ac56a8ba6a3c1c7bd9fc66
Bug 1006248. Part 3: Add lots of system header wrappers for B2G/Android. r=glandium

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extra : rebase_source : 8ea21e177bf6f5ba7bb9d53c8f564b46e8b97cd6
Bug 1006248. Part 4: Use better #include paths for libstagefright headers in a couple of places. r=glandium

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extra : rebase_source : e8c7e019b0bc5bf60081aad158a7d89fbb261e29