scripts: Properly declare g_auto() stub for cocci

While being great semantic patching tool, coccinelle fails to
understand some of macros we use (including those provided by
glib). What they have in common is use of __attribute__ under the
hood. We store a list of such macros in a file. But in there,
g_auto() macro is not defined properly. Indeed, g_auto(type)
declares a local variable of given type, for instance from
cocci's POV:

  g_auto(virBuffer) buf = VIR_BUFFER_INITIALIZER;
  virBuffer buf = VIR_BUFFER_INITIALIZER;

are both the same declaration. Fix declaration of g_auto() stub.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Tim Wiederhake <twiederh@redhat.com>

scripts/cocci-macro-file.h

@@ -34,6 +34,6 @@
 
 #define g_autoptr(x) x##_autoptr
 #define g_autofree
-#define g_auto
+#define g_auto(x) x
 
 #define BAD_CAST