Remove unused OI variable, unindent better.
 [rsc] --rw-rw-r-- M 191333 glenda sys 23027 Sep 22 08:58 sys/lib/tmac/tmac.s
	/n/sourcesdump/2005/0922/plan9/sys/lib/tmac/tmac.s:827,833 - 
	/n/sourcesdump/2005/0923/plan9/sys/lib/tmac/tmac.s:827,832
	  .
	  .de P1
	  .nr P1 .4i	\" program indent in .P1
	- .nr OI .4i
	  .if \\n(.$ .nr P1 \\$1
	  .br
	  .nr v \\n(.v
	/n/sourcesdump/2005/0922/plan9/sys/lib/tmac/tmac.s:847,853 - 
	/n/sourcesdump/2005/0923/plan9/sys/lib/tmac/tmac.s:846,852
	  .vs \\n(VSp
	  .vs \\nvu
	  .ft 1
	- .in
	+ .in -\\n(P1u
	  .di
	  .br
	  .sp \\n(DVu