don't print (incorrect anyway) line numbers in panic.

R=rsc
DELTA=4  (0 added, 2 deleted, 2 changed)
OCL=19757
CL=19763

src/runtime/runtime.c

@@ -23,9 +23,7 @@ sys·panicl(int32 lno)
 {
 	uint8 *sp;
 
-	prints("\npanic on line ");
-	sys·printint(lno);
-	prints(" ");
+	prints("\npanic ");
 	sys·printpc(&lno);
 	prints("\n");
 	sp = (uint8*)&lno;

test/golden.out

@@ -146,7 +146,7 @@ BUG: should compile
 =========== bugs/bug119.go
 3 74256
 
-panic on line 85 PC=xxx
+panic PC=xxx
 BUG: should not fail
 
 =========== bugs/bug120.go