test: filter out messages when stripping binaries

We would get an error for every script, which is just noise.

test/test-functions

@@ -560,7 +560,10 @@ strip_binaries() {
         return 0
     fi
     ddebug "Strip binaries"
-    find "$initdir" -executable -not -path '*/lib/modules/*.ko' -type f | xargs strip --strip-unneeded | ddebug
+    find "$initdir" -executable -not -path '*/lib/modules/*.ko' -type f | \
+        xargs strip --strip-unneeded |& \
+        grep -v 'file format not recognized' | \
+        ddebug
 }
 
 create_rc_local() {