[kernel] Fixes attribute annotations for formals

src/kernel_internals/parsing/cparser.mly

@@ -1528,7 +1528,7 @@ attribute:
 |   VOLATILE              { ("volatile",[]), $1 }
 |   GHOST                 { ("ghost",[]), $1 }
 |   ATTRIBUTE_ANNOT       { let annot, loc = $1 in
-			    ("$annot:" ^ annot, []), loc }
+			    (Cil.mkAttrAnnot annot, []), loc }
 ;
 
 /* (* sm: I need something that just includes __attribute__ and nothing more,

tests/spec/ghost_attribute.i

+void foo(int* p /*@ my_attribute */){
+  int /*@ my_attribute */ v ;
+}

tests/spec/oracle/ghost_attribute.res.oracle

+[kernel] Parsing tests/spec/ghost_attribute.i (no preprocessing)
+/* Generated by Frama-C */
+void foo(int *p /*@ my_attribute */)
+{
+  int /*@ my_attribute */ v;
+  return;
+}
+
+