[Stuart Shelton]

(In the attached patch, the removal of 'const' from casts in a couple of files is only to remove a few cosmetic compiler warnings)

This patch should, so far as I can tell, be portable across all platforms.

With these changes, the test-suite has only one failure:

Generating streams...
ERROR during test_streams
FAIL: ./test_flac.sh

... which is caused by src/test_streams/test_streams, which fails silently.

Patch to address IRIX build failures