Removes dependency of HTJ2K Compressor on realloc()

[palemieux]

Closes #2060

exrmetrics write time before the patch:

 .\bin\Release\exrmetrics.exe  "C:\Users\pal\scratch\OpenEXR\SPARKS_4K_P3_PQ_4000nits_EXR\500-skip\SPARKS_P3_PQ_4000nit_02500.exr" -z htj2k
    {
      "compression": "htj2k",
      "pixel mode": "original",
      "output size": 25219604,
      "read time": 0.0361311,
      "write time": 4.79588,
      "re-read time": 0.188013
    }

exrmetrics write time after the patch:

 .\bin\Release\exrmetrics.exe  "C:\Users\pal\scratch\OpenEXR\SPARKS_4K_P3_PQ_4000nits_EXR\500-skip\SPARKS_P3_PQ_4000nit_02500.exr" -z htj2k
    {
      "compression": "htj2k",
      "pixel mode": "original",
      "output size": 25219604,
      "read time": 0.0268385,
      "write time": 0.296235,
      "re-read time": 0.169697
    }

[cary-ilm]

@kdt3rd, this seems fine to me but can you look this over?

[cary-ilm]

Looks fine, thanks.

@palemieux, can you update the branch?

[palemieux]

@cary-ilm Done