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.

Merged in david_s5/nuttx/upstream_revert_265af481 (pull request #194)

Revert "STM32 serial: Make input hardware flow-control work with RX DMA.  From Jussi Kivilinna"

HSI should not be turned off

This reverts commit 4e051c05.

This change broke the STM32 seril driver.