* check/stack.ok, check/stack.tst: New files to test data
integrity on a deep chain of stack frames.
* lib/jit_arm.c, lib/jit_arm-cpu.c, lib/jit_mips.c,
lib/jit_mips-cpu.c, lib/jit_ppc.c, lib/jit_ppc-cpu.c,
lib/jit_x86.c, lib/jit_x86-cpu.c: Calculate _jit->function->stack
in the emit stage, otherwise it will calculate it wrong if
need to jit_allocai space to spill registers.
* lib/lightning.c: Correct wrong offset when updating the
"current" jit function pointer in the code that may need to
allocate stack space to spill registers.
* check/lightning.c: Correct off by one data space check.
* check/Makefile.am: Update for new test case.
