Fix magicFillTarget getting lowered if dying during refill

[djevangelia]

Don't change magicFillTarget if player dies during magic fill. Fixes #1618.

When player dies, the magic fill target when respawning is set to current magic, and current magic is then set to 0. If player respawns and dies before magic is fully refilled, the fill target will be changed to player's current magic again, i.e. less than previous target.

This fix checks on game over if player is currently in a refill state: either FILL state, drawing the magic bar extending (STEP_CAPACITY), or has a magicLevel of 0 (set when dying, reset early when starting magic refill). If so, it does not overwrite the old fill target.

The assembly should roughly be equal to:

if (gSaveContext.magicState != MAGIC_STATE_FILL && gSaveContext.magicState != MAGIC_STATE_STEP_CAPACITY &&
    gSaveContext.save.info.playerData.magicLevel != 0) {
    gSaveContext.magicFillTarget = gSaveContext.save.info.playerData.magic;
}
gSaveContext.magicCapacity = 0;
gSaveContext.save.info.playerData.magicLevel = gSaveContext.save.info.playerData.magic = 0;

where the gSaveContext.magicFillTarget was previously always set.

Disassembly

Part of matching Kaleidoscope_Update disassembly here (it's 2500+ lines long in full)
Decomp C code here

Testing

Tested in Ares recently nightly build and Project64 3.0.1.
Looks like this: https://www.youtube.com/watch?v=s4WrGXN75-E

Instant death function for testing:

func_80837B18 = 0x8038e5b4;
extern int32_t func_80837B18(z64_game_t* play, z64_link_t* this, int32_t damage);
if (z64_game.common.input[0].raw.pad.dr) {
    func_80837B18(&z64_game, &z64_link, -200);
}