Remove attempt to test system header from tests/plugin/callgraph

(The output varied too much between different compiler releases)

Author: davidmalcolm

tests/plugin/callgraph/input.c

@@ -17,13 +17,8 @@
    <http://www.gnu.org/licenses/>.
 */
 
-#include <stdio.h>
-
-extern const char *name;
-
 void foo()
 {
-    printf ("hello %s\n", name);
 }
 
 void bar(void)

tests/plugin/callgraph/stdout.txt

@@ -56,15 +56,6 @@ class CallgraphEdge(__builtin__.object)
  |  __new__ = <built-in method __new__ of gcc.WrapperMeta object>
  |      T.__new__(S, ...) -> a new object with type S, a subtype of T
 
-cgn:
-  cgn.decl: gcc.FunctionDecl('printf')
-  cgn.decl.location.in_system_header: True
-  cgn.callers: [gcc.CallgraphEdge()]
-  cgn.callees: []
-gcc.CallgraphEdge()
-e.caller: gcc.CallgraphNode()
-e.callee: gcc.CallgraphNode()
-e.call_stmt: gcc.GimpleCall() printf ("hello %s\n", name.0);
 cgn:
   cgn.decl: gcc.FunctionDecl('baz')
   cgn.decl.location.in_system_header: False
@@ -91,7 +82,7 @@ cgn:
   cgn.decl: gcc.FunctionDecl('foo')
   cgn.decl.location.in_system_header: False
   cgn.callers: [gcc.CallgraphEdge(), gcc.CallgraphEdge(), gcc.CallgraphEdge()]
-  cgn.callees: [gcc.CallgraphEdge()]
+  cgn.callees: []
 gcc.CallgraphEdge()
 e.caller: gcc.CallgraphNode()
 e.callee: gcc.CallgraphNode()