libfdk-aacdec: Make sure decoding doesn't add any extra delay in the latest version of fdk-aac

The latest version added support for a new option for enabling
a signal level limiter, which adds some extra delay. In fdk-aac, this
is enabled by default, but disable it by default here since we'd rather
have zero-delay decoding.

Signed-off-by: Martin Storsjö <martin@martin.st>
