Squashed commit of the following:

libs/libc/pthread/pthread_spinlock.c:  Resolve several TODO issues by accessing up_testset() via the boardctl() interface rather than attempting to call it directly.

    configs/boardctl.c, include/sys/boardctl.h:  Add access to architecture-specific up_testset() via boardctl().

    arch/Kconfig's, sched/Kconfig, and include/nuttx/spinlock.h:  Spinlocks are not available unless the architecture supports the up_testset() operation.

arch/Kconfig

@@ -66,6 +66,7 @@ config ARCH_SIM
 	select ARCH_HAVE_TLS
 	select ARCH_HAVE_TICKLESS
 	select ARCH_HAVE_POWEROFF
+	select ARCH_HAVE_TESTSET
 	select SERIAL_CONSOLE
 	---help---
 		Linux/Cywgin user-mode simulation.
@@ -79,6 +80,7 @@ config ARCH_XTENSA
 	bool "Xtensa"
 	select ARCH_HAVE_STACKCHECK
 	select ARCH_HAVE_CUSTOMOPT
+	select ARCH_HAVE_TESTSET
 	---help---
 		Cadence® Tensilica® Xtensa® actictures.
 
@@ -221,6 +223,10 @@ config ARCH_HAVE_RESET
 	bool
 	default n
 
+config ARCH_HAVE_TESTSET
+	bool
+	default n
+
 config ARCH_HAVE_FETCHADD
 	bool
 	default n