Implement WNOHANG for waitpid() only and for the case of CONFIG_SCHED_HAVE_PARENT not selected.  From Max Neklyudov.

STMPE811: I found that, in stmpe811_instanciate(), when CONFIG_STMPE811_MULTIPLE is enabled, and the call to stmpe811_checkid() fails, then the linked device list is not restored to its previous state.  From Sebastien Lorquet.

drivers/net/slip.c:  Fix a missed name change when many of network interface names changed sometime back but were apparently never updated for SLIP

include/nuttx/net/netconfig.h:  Fix some backward compilation that was emitting #error in the wrong condition when SLIP was enabled

Fix a Cortex-A compilation error in the vfork() logic when system calls are enabled in modes other than CONFIG_BUILD_KERNEL.

arch/arm/src/sama5/sam_ehci.c:  Fix some bad conditional compilation that left a function undefined if CONFIG_USBHOST_ASYNCH is not selected.

Group binding needs to be cleared before sched_releasetcb(), as otherwise group_leave() will be called and group->tg_nmembers decremented or group being released. group_leave() should be called only after group_join() is called, not after group_bind().  From Jussi Kivilinna.

tools/testbuild.sh:  Add a script that can be used perform test builds on a set of board configurations