[Reduction] #173: bgm_set_tempo
[Reduction] #174: bgm_mget
[Reduction] #175: bgm_pinit
[Reduction] #176-177: bgm_play

[Binary change] Order of 3 relocations in TH04's MAINE.EXE and TH05's OP.EXE
and MAINE.EXE.
[Reduction] #178: bgm_effect_sound
[Reduction] #179: bgm_stop_play