more "declared and not used".

the last round omitted := range and only
checked 1 out of N vars in a multi-var :=

R=r
OCL=34624
CL=34638
diff --git a/src/pkg/log/log.go b/src/pkg/log/log.go
index c109efa..3d48285 100644
--- a/src/pkg/log/log.go
+++ b/src/pkg/log/log.go
@@ -97,7 +97,7 @@
 		}
 	}
 	if l.flag & (Lshortfile | Llongfile) != 0 {
-		pc, file, line, ok := runtime.Caller(calldepth);
+		_, file, line, ok := runtime.Caller(calldepth);
 		if ok {
 			if l.flag & Lshortfile != 0 {
 				short, ok := shortnames[file];