work around missing RLIMIT_AS

Index: test-suite/standalone/test-out-of-memory
--- test-suite/standalone/test-out-of-memory.orig
+++ test-suite/standalone/test-out-of-memory
@@ -41,10 +41,10 @@ exec guile -q -s "$0" "$@"
 ;; 50 MB.
 (define *limit* (* 50 1024 1024))
 
-(call-with-values (lambda () (getrlimit 'as))
+(call-with-values (lambda () (getrlimit 'data))
   (lambda (soft hard)
     (unless (and soft (< soft *limit*))
-      (setrlimit 'as (if hard (min *limit* hard) *limit*) hard))))
+      (setrlimit 'data (if hard (min *limit* hard) *limit*) hard))))
 
 (define (test thunk)
   (catch 'out-of-memory
