Mess with BRR decoding for hopefully the last time

[PhoenixBound]

• Finally use the BRR filter formulas provided in fullsnes, instead of ones that approximate the exact rounding. For some very short, unstable samples, this has been shown to result in a completely different sound.
• Up the max iteration count for samples, since 64 doesn't cut it anymore (and didn't really work for many non-EarthBound games, before this change).
• Don't override the range to 0 for the first block of a sample, since homebrew non-glitch samples may store something other than silence in the first block.
• In anticipation of one day turning on UBSan, get rid of a left shift of a potentially negative number, and turn it into a multiplication. A left shift like this is undefined behavior in C (but not C++). gcc 13 seems to optimize the "* (1 << n)" pattern when UBSan is on just fine.