Removed RTC driftfix option for non-Windows/ReactOS/DOS guests

According to the QEMU man page:

    Enable driftfix (i386 targets only) if you experience time
    drift problems, specifically with Windows' ACPI HAL. This
    option will try to figure out how many timer interrupts were
    not processed by the Windows guest and will re-inject them.

This option thus seems unnecessary for other systems and may cause
performance or timekeeping issues, so enable only for
Windows/ReactOS/DOS.

quickemu

@@ -1212,7 +1212,7 @@ function vm_boot() {
         args+=(-rtc base=localtime,clock=host,driftfix=slew)
     else
         # shellcheck disable=SC2054
-        args+=(-rtc base=utc,clock=host,driftfix=slew)
+        args+=(-rtc base=utc,clock=host)
     fi
 
     # shellcheck disable=SC2206