Replace void with int to make this a valid C++ file.

The test was passing because clang would still print the ast before exiting
with an error. Since that didn't seem to be the intent of the test, I change
the test instead of adding 'not' to the command line.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@185634 91177308-0d34-0410-b5e6-96231b3b80d8

test/CXX/dcl.dcl/dcl.link/p7-2.cpp

 // RUN: %clang_cc1 -ast-print -o - %s | FileCheck %s
 
-extern "C" void f(void);
-// CHECK: extern "C" void f()
+extern "C" int f(void);
+// CHECK: extern "C" int f()
 
-extern "C" void v;
-// CHECK: extern "C" void v
+extern "C" int v;
+// CHECK: extern "C" int v