Add some experimental changes to enter/leave_critical_section to deal with the case where interrupts are disabled only on the local CPU

If SMP is enabled, if any interrupt handler calls enter_critical_section(), it should take the spinlock.

sched/irq:  Change order for SMP case in enter_critical_section:  Disble local interrupts BEFORE taking spinlock.

SAMV7 USBDEVHS: A problem occurred if the USB cable is unplugged while a large amount of data is send over an IN endpoint using DMA. If the USB cable is plugged in again after a few seconds it is not possible to send data over this IN endpoint again, all other endpoints work as expected.

The problem occurs because if the USB cable is unplugged while an DMA transfer is in flight the transfer is canceled but the register SAM_USBHS_DEVDMACTRL is left in an undefined state.  The problem was fixed the problem by resetting the register SAM_USBHS_DEVDMACTRL to a known state. Additionally all pending interrupts are cleared.

Misoc LM32: Corrects a bug that never occured in qemu on simulation or real fpga. The error was that the r1 register was being modified out of context switching and not restoring it.

Patch brings strtol() and related functions more conformant with POSIX.  Corner cases like strtol(-2147483648, NULL, 10) now pass clang -fsanitize=integer without warnings.

typos

Change the way to configure quadrature encoder prescalers.