SAM3/4: Add support for ATSAM4S4C.

STM32L4:  Port fix for multiple oneshot timers from STM32.  Also fixes a few issues with original STM32 implementation.

Fixed some issues that prevented ipv6 to work with ipv4 enabled.

drivers/:  Remove all explicit use of 'hidden' macro _info.  Code must never use this directly.  Code must always use a debug macro such as info which is basic on _info but can be appropriately filtered.

SMP Signals: Fix some SMP signal delivery logic. Was not handling some critical sections correctly and was missing logic to signal tasks running on other CPUs.

SMP: Fix an error in critical section logic when performing a context switch from an interrupt handler.  The g_cpu_irqset bit was not being set for the CPU so other CPUs did not know about the critical section.