Fix running Super Mario when built with GCC 11

[gunnarbeutner]

Super Mario crashes when built with GCC 11. It seems that GCC re-orders the static initializers in a way that break assumptions made in Music::Music. Here's the stack trace I got:

CrashDaemon(15): New coredump file: /tmp/coredump/uMario_27_1619674230
CrashDaemon(15): --- Backtrace for thread #0 (TID 27) ---
CrashDaemon(15): 0x6b2360a8: [/opt/Super_Mario/uMario] Music::Music() +0x50
CrashDaemon(15): 0x6b1bd4e6: [/opt/Super_Mario/uMario] __static_initialization_and_destruction_0(int, int) +0xb6
CrashDaemon(15): 0x6b1bd594: [/opt/Super_Mario/uMario] _GLOBAL__sub_I__ZN4CCFGC2Ev +0x1f```

This PR changes how those singletons are initialized.