Add sparc64, amd64.
 [rsc] --rw-rw-r-- M 320859 glenda sys 2698 Oct 27 10:52 sys/src/ape/lib/ap/syscall/mkfile
	/n/sourcesdump/2005/1027/plan9/sys/src/ape/lib/ap/syscall/mkfile:63,69 - 
	/n/sourcesdump/2005/1028/plan9/sys/src/ape/lib/ap/syscall/mkfile:63,78
	  				MOVL AX,4(CX)'
	  			}
	  			echo RET
	- 		case sparc
	+ 		case amd64
	+ 			if(~ $i _SEEK)
	+ 				echo TEXT __SEEK'(SB)', 1, '$0'
	+ 			if not
	+ 				echo TEXT $i'(SB)', 1, '$0'
	+ 			echo MOVQ RARG, 'a0+0(FP)'
	+ 			echo MOVQ '$'$n, RARG
	+ 			echo SYSCALL
	+ 			echo RET
	+ 		case sparc sparc64
	  			echo TEXT $i'(SB)', 1, '$0'
	  			echo MOVW R7, '0(FP)'
	  			echo MOVW '$'$n, R7