CAN support for STM32L4

SAM WDT: Rename up_wdginitialize() functions to something more appropriate for the internal OS interface.

SAM WDT: Rename up_wdginitialize() functions to something more appropriate for the internal OS interface.

enter/leave_critical_section:  In SMP configuration, may attempt to access the task lists before they have been initialized

Fixed Break changes needed CONFIG_SERIAL_TERMIOS to build

Upstream_to_greg

All GCC final arch/*/src/Makefiles: Allow --start-group and --end-group to be redefined for the case where GCC is used to link (instead of LD).  Suggested by Paul Alexander Patience.

wfi.mac should be copied into the directory with the IAR project. Then set it to "Options -> Debugger -> Setup macro file(s)". This will allow debugging via JTAG when calling the WFI instruction.