Removed redundant __buffsize (SAS/C (AmigaOS))
No GTK on Amiga. :(
Included the correct quantize header. (quantize-pvt.h instead of quantize.h)
Fixed M_PI/M_SQRT2 to work on all platforms. Removed unused INLINE.
Removed write_ancillary_data() prototype. (No longer used)
Adjusted PI/SQRT2 precision. (SQRT2 deviated from standard math.h value)
Added new PI and LOG predefined variants, and stuck them in at respective places.
Changed M_PI to PI. (Not everyone has M_PI, but PI is always defined in util.h)