Implement the jit_align interface

* lib/jit_aarch64-cpu.c, lib/jit_alpha-cpu.c, lib/jit_arm-cpu.c,
	lib/jit_hppa-cpu.c, lib/jit_mips-cpu.c, lib/jit_ppc-cpu.c,
	lib/jit_sparc-cpu.c: Implement or correct the internal
	nop(count) call that receives an argument that tells the
	modulo bytes to align the code for the next instruction.

	* include/lightning.h, lib/lightning.c, lib/jit_aarch64.c,
	lib/jit_alpha.c, lib/jit_arm.c, lib/jit_hppa.c, lib/jit_ia64.c,
	lib/jit_mips.c, lib/jit_ppc.c, lib/jit_s390x.c, lib/jit_sparc.c,
	lib/jit_x86.c: Implement the new jit_align() call that receive
	an argument, that tells the modulo, in bytes, to align the
	next instruction. In most backends the only value that makes
	a difference is a value that matches sizeof(void*), as all
	other values usually are already automatically aligned in
	labels, but not guaranteed to be aligned at word size bytes.

	* check/align.ok, check/align.tst: New files, implementing
	a simple test for the new jit_align() interface.

	* check/Makefile.am, check/lightning.c, lib/jit_aarch64-sz.c,
	lib/jit_alpha-sz.c, lib/jit_arm-sz.c, lib/jit_hppa-sz.c,
	lib/jit_ia64-sz.c, lib/jit_mips-sz.c, lib/jit_ppc-sz.c,
	lib/jit_print.c, lib/jit_s390x-sz.c, lib/jit_sparc-sz.c,
	lib/jit_x86-sz.c: Update for the new jit_code_align code and
	the jit_align() interface.

include/lightning.h

@@ -177,7 +177,8 @@ typedef enum {
 #define jit_data(u,v,w)		_jit_data(_jit,u,v,w)
     jit_code_data,
 #define jit_live(u)		jit_new_node_w(jit_code_live, u)
-    jit_code_live,
+#define jit_align(u)		jit_new_node_w(jit_code_align, u)
+    jit_code_live,		jit_code_align,
     jit_code_save,		jit_code_load,
 #define jit_name(u)		_jit_name(_jit,u)
     jit_code_name,