Adapt PowerPC port to work in Darwin 32 bit and Linux 64 bit.

* include/lightning.h: Add check for __powerpc__ defined
	in Linux, while Darwin defines __ppc__.

	* include/lightning/jit_ppc.h: Adjust register definitions
	for Darwin 32 bit and Linux 64 bit ppc usage and/or ABI.

	* include/lightning/jit_private.h: Add proper check for
	Linux __powerpc__ and an data definition for an workaround
	to properly handle code that starts with a jump to a "main"
	label.

	* lib/jit_disasm.c: Add extra disassembler initialization
	for __powerpc64__.

	* lib/jit_ppc-cpu.c: Add extra macros and functions, and
	correct/adapt previous ones to handle powerpc64.

	* lib/jit_ppc-fpu.c: Adapt for 64 bit wordsize. Basically
	add conversion from/to int32/int64 and proper handling of
	load/store offsets too large for 32 bit.

	* lib/jit_ppc.c: Add calls to 64 bit codes and adaptation
	for the PowerPC 64 bit Linux ABI.

	* lib/jit_arm.c, lib/jit_mips.c, lib/jit_sparc, lib/jit_x86.c,
	lib/lightning.c: Correct off by one error when restarting jit
	of a function due to finding too late that needs to spill/reload
	some register. Problem was found by accident on a very special
	condition during PowerPC 64 code adaptation.

lib/jit_mips.c

@@ -1186,6 +1186,7 @@ _emit_code(jit_state_t *_jit)
 			    temp->code == jit_code_epilog)
 			    temp->flag &= ~jit_flag_patch;
 		    }
+		    temp->flag &= ~jit_flag_patch;
 		    node = undo.node;
 		    _jit->pc.w = undo.word;
 		    _jitc->patches.offset = undo.patch_offset;