* include/lightning.h, include/lightning/jit_private.h,
lib/jit_names.c, lib/lightning.c: Add initial support
for the new jit_va_start, jit_va_arg, jit_va_arg_d, and
jit_va_end interfaces. The jit_va_start call is supposed
to return a va_list compatible pointer, but not yet
decided if it will be "declared" stdarg compatible,
as for now only x86 support has been added (and should
be compatible), but issues may arise on other backends.
* check/lightning.c: Add wrappers to call the new jit_va_*
interfaces.
* lib/jit_x86-cpu.c, lib/jit_x86.c: Implement the new
jit_va_* for x86.
* lib/jit_x86-sz.c: Add fields, but not yet fully updated,
as this is an intermediate commit.
* lib/jit_aarch64-sz.c, lib/jit_aarch64.c,
lib/jit_alpha-sz.c, lib/jit_alpha.c,
lib/jit_arm-sz.c, lib/jit_arm.c,
lib/jit_hppa-sz.c, lib/jit_hppa.c,
lib/jit_ia64-sz.c, lib/jit_ia64.c,
lib/jit_mips-sz.c, lib/jit_mips.c,
lib/jit_ppc-sz.c, lib/jit_ppc.c,
lib/jit_s390-sz.c, lib/jit_s390.c,
lib/jit_sparc-sz.c, lib/jit_sparc.c: Prepare for the
new jit_va_* interfaces. Not yet implemented, and will
cause an assertion if used.
* check/va_list.tst: Simple early test case, that works
on x86_64, x32, ix86, cygwin, and cygwin64.
