machine/8042kbdc.cpp: BeOS 3.x/4.x erratic keyboard

[angelosa]

Steps to reproduce (shortest way):

1. grab a BeOS 3.x x86 floppy disk;
2. mamefoo pcipc -flop1 <pathto>bootdisk.img (HDD/CD doesn't matter)
3. Most often the "Press Space Bar for boot options" doesn't work (necessary for loading from CD), wait until it prompts you to select Boot Options;

None of the keyboard scancodes seems to match what the system expects, this is also repeated in an actual BeOS 4.0 installation, where only mouse works while keyboard gets detected with wrong & stuck keys in Keymap tool.

BeOS 3.1 notes:

1. PC=401eae cmp eax,0h, eax always 1
2. Following snippet for the scancode interpretation (roughly enter/esc/directional arrows as also prompted by the SW):

   00413D86: 89 45 E0          mov     [ebp-20h],eax
   00413D89: 8B 45 E0          mov     eax,[ebp-20h]
   00413D8C: 2D 57 00 00 00    sub     eax,57h
   00413D91: 74 3C             je      413DCFh
   00413D93: 2D 0B 00 00 00    sub     eax,0Bh
   00413D98: 0F 84 85 00 00 00 je      413E23h
   00413D9E: 2D C4 FF FF FF    sub     eax,0FFFFFFC4h
   00413DA3: 0F 84 CA 00 00 00 je      413E73h
   00413DA9: 2D DB FF FF FF    sub     eax,0FFFFFFDBh
   00413DAE: 0F 84 31 01 00 00 je      413EE5h
   00413DB4: 2D 46 00 00 00    sub     eax,46h
   00413DB9: 0F 84 2D 01 00 00 je      413EECh
   00413DBF: 2D 14 00 00 00    sub     eax,14h
   00413DC4: 0F 84 22 01 00 00 je      413EECh
   00413DCA: E9 70 01 00 00    jmp     413F3Fh

[angelosa]

Related to #11797 ?