avcfg: Override type of bitrate property from int64 to int

See gstreamer/gst-libav#41 (comment 142808)

The switch to the new ffmpeg property system changed the type of the
bitrate property from int to int64, which potentially breaks many
existing applications at runtime as properties are usually set via
g_object_set().

As such, override the type to int until GStreamer 2.0.
11 jobs for avenc-bitrate-int in 39 minutes and 50 seconds (queued for 1 second)
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gst indent

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build fedora x86_64

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check fedora

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build cerbero android universal

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android universal examples

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