use errchk in more places.
let errchk exit 0 even if it has reported a BUG.
it echoed BUG and that's all that matters.

R=r
DELTA=143  (1 added, 89 deleted, 53 changed)
OCL=32533
CL=32542
diff --git a/test/fixedbugs/bug037.go b/test/fixedbugs/bug037.go
index b0345cc..ff7d287 100644
--- a/test/fixedbugs/bug037.go
+++ b/test/fixedbugs/bug037.go
@@ -7,5 +7,5 @@
 package main
 
 func main() {
-	s := vlong(0);  // BUG no vlong specified in the language
+	s := vlong(0);  // ERROR "undef"
 }