Skip testsuite/g++.old-deja/g++.pt/const2.C on vxworks_kernel

Linking in vxworks kernel-mode is partial linking, so missing symbols
are not detected.


for  gcc/testsuite/ChangeLog

	* g++.old-deja/g++.pt/const2.C: Skip on vxworks kernel.

gcc/testsuite/g++.old-deja/g++.pt/const2.C

 // { dg-do link }
+// { dg-skip-if "VxWorks dkms use partial link" { vxworks_kernel } }
 // This test should get a linker error for the reference to A<int>::i.
 // { dg-prune-output "ld: symbol" }
 // { dg-message "i" "" { target *-*-* } 0 }