Added missing guards against --disable-save-state
Removed Windows relevant code.
misc.c clean up part 1:

Removed the following values:
---------------------------------------------------------------------
logging_started, tablet, axmax, aymax, azmax, xmax, ymax, zmax, xres,
yres, maxpres, tabletname, tablet_x, tablet_y, tablet_z,
tablet_pressure, tablet_buttons, tablet_proximity, tablet_ax,
tablet_ay, tablet_az, tablet_flags, log_scsi, log_net, uaelib_debug,
struct winuae_currentmode, currentmodestruct, *currentmode,
serial_period_hsyncs, serial_period_hsync_counter, data_in_serdir,
log_vsync, debug_vsync_min_delay, debug_vsync_forced_delay,
tablet_log

Removed the following related functions:
---------------------------------------------------------------------
void serial_hsynchandler (void);
void serial_check_irq (void);
save_log()
misc.c clean up part 2:

Removed the following values:
---------------------------------------------------------------------
seriallog, rawkeyboard, rawinput_enabled_mouse,
rawinput_enabled_keyboard, int no_rawinput, usedfilter,
vblank_found_chipset, vsyncmemory, wasfullwindow_a, wasfullwindow_p,
vblankbasewait1, vblankbasewait2, vblankbasewait3, vblankbaselace,
vblankbaselace_chipset, vblankthread_oddeven

Removed the following related functions:
---------------------------------------------------------------------
int is_tablet(void)
getdisplay()
bool target_graphics_buffer_update (void);
vblank_calibrate()
vblanklaceskip()
vblanklaceskip_check()
misc.c clean up part 3:

Removed the following values:
---------------------------------------------------------------------
vblank_found, flipthread_mode, vblank_found_rtg, flipevent,
flipevent2, vblankwaitevent, flipevent_mode, remembered_vblank,
vblankthread_mode, vblankthread_counter, vblankbasewait,
vblankbasefull, vblank_found_flipdelay, thread_vblank_time,
vblank_skipeveryother, vblank_first_time

Removed the following related functions:
---------------------------------------------------------------------
vsync_busywait_end()
doflipevent()
waitflipevent()
changevblankthreadmode_do()
getcurrentvblankrate()
changevblankthreadmode()
changevblankthreadmode_fast()
vsync_busywait_start()
misc.c clean up part 4

Removed the following values:
---------------------------------------------------------------------
frame_missed, frame_errors, frame_usage, frame_usage_avg
frame_usage_total, frame_counted, dooddevenskip, vblank_flip_delay,

Removed the following related functions:
---------------------------------------------------------------------
vsync_isdone()
D3D_goodenough()
DirectDraw_CurrentRefreshRate()
DirectDraw_GetVerticalBlankStatus()
serialuartbreak()
serial_uartbreak()

Further cleaned up:
---------------------------------------------------------------------
Moved several prototypes from misc.c to misc.h and removed external
prototypes in other compilation units.
Cleaned up .gitignore to be better readable and maintainable.
Fixed some mistakes from misc.c cleaning.