Add the jit_callee_save_p interface and extra register definitions.

* check/self.c, check/self.ok: New files implementing simple
	consistency check assertions. At first validating some macros
	that use values from different sources agree.

	* check/Makefile.am: Update for the new test case.

	* include/lightning.h,  lib/lightning.c: Add the new
	jit_callee_save_p() call, that is intended to be used when
	writing complex code using lightning, so that one does not
	need to verify what backend is being used, or have access to
	private data, to query if a register is callee save or not;
	on several backends the scratch registers are actually callee
	save.

	* include/lightning/jit_aarch64.h, include/lightning/jit_arm.h,
	include/lightning/jit_hppa.h, include/lightning/jit_mips.h,
	include/lightning/jit_ppc.h, include/lightning/jit_sparc.h,
	include/lightning/jit_x86.h: Add an explicit definition for
	JIT_R3-JIT_Rn, JIT_V3-JIT_Vn and JIT_F6-JIT_Fn when applicable.
	This allows one to write code based on "#if defined(JIT_XN)"
	and therefore, not need to check what is the current backend
	or have access to private data structures. This is particularly
	useful when writing virtual machines with several specialized,
	global registers.

	* lib/jit_ia64.c: Properly flag the callee save general
	purpose registers as such, so that jit_callee_save_p() works
	as intended.

lib/lightning.c

@@ -330,6 +330,13 @@ _jit_unget_reg(jit_state_t *_jit, jit_int32_t regno)
     jit_regset_clrbit(&_jitc->regarg, regno);
 }
 
+jit_bool_t
+_jit_callee_save_p(jit_state_t *_jit, jit_int32_t regno)
+{
+    assert(regno >= 0 && regno < JIT_NOREG);
+    return (!!(_rvs[regno].spec & jit_class_sav));
+}
+
 #if __ia64__
 void
 jit_regset_com(jit_regset_t *u, jit_regset_t *v)