Fix crash during runtime arraymode change

 - Handle array mode changes for null c2Buffer.
   Since enabling flag can change buffers to arrayMode during runtime,
   reallocation of buffers may fails if the output comes with a null
   c2Buffer. This change will handle null c2Buffer reallocation using
   the information before the change or assume a default of LINEAR
   bufferType.

Bug: 418813731
Flag: android.media.codec.remove_arraymode_for_linear_output_buffers
Test: atest android.mediav2.cts.CodecEncoderMultiAccessUnitTest
      atest android.mediav2.cts.CodecDecoderTest
      atest android.mediav2.cts.CodecDecoderBlockModelMultiAccessUnitTest

Change-Id: I98db9504b0bb680d220cb4695a58458409525194