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

Fix references to the no-longer-existent misc/ directory in comments, README files, and documentation

NFS: Fix prototype of unbind method.  The function prototype was not updated for NFS after a recent change to the file system interface.  From Manuel Stühn.

In ARMV71-Xplained clock configuration, divider was set to 25 to get 25*12MHz=300MHz CPU clock.  The correct multiplier is 24 becaue the calculatin if (24+1)*12MHz.  So the board was running at 312MHz.  From Efim Monjak.