test: minor fixes in run and testlib

Can tell this doesn't get run very often, but it is still important
for when you've broken everything else.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6547065

test/run

@@ -54,6 +54,8 @@ true >pass.out >times.out
 exclude=false	# exclude nothing
 golden=golden.out
 
+rm -f tmp.go  # generated by some tests, left behind if interrupted
+
 filterout() {
 	grep '^'"$2"'$' $1 >/dev/null
 }

test/testlib

@@ -12,7 +12,7 @@ compile() {
 compiledir() {
 	for gofile in $D/$F.dir/*.go
 	do
-		$G ${gofile} || return 1
+		$G -I. "$gofile" || return 1
 	done
 }