Avoid a deprecation warning

https://bugzilla.gnome.org/show_bug.cgi?id=711547
win32: silence build warning

glocalfileinfo.c: In function '_g_local_file_info_get':
glocalfileinfo.c:1955:11: warning: passing argument 3 of
'get_thumbnail_attributes' from incompatible pointer type [enabled by
default]
           get_thumbnail_attributes (path, info, &statbuf);
           ^
glocalfileinfo.c:1285:1: note: expected 'const struct GStatBuf *' but
argument is of type 'struct _stati64 *'
 get_thumbnail_attributes (const char     *path,

https://bugzilla.gnome.org/show_bug.cgi?id=711547
win32: silence build warning

gdbusauthmechanismexternal.c: In function 'mechanism_client_initiate':
gdbusauthmechanismexternal.c:355:3: warning: 'initial_response' may be
used uninitialized in this function [-Wmaybe-uninitialized]
   return initial_response;
   ^
gdbusauthmechanismexternal.c:332:10: note: 'initial_response' was
declared here

https://bugzilla.gnome.org/show_bug.cgi?id=711547
win32: silence build warning

glocalfile.c: In function 'g_local_file_measure_size_of_file':
glocalfile.c:2654:3: warning: passing argument 2 of 'g_lstat' from
incompatible pointer type [enabled by default]
   if (g_lstat (name->data, &buf) != 0)
   ^
In file included from glocalfile.c:68:0:
../glib/gstdio.h:135:5: note: expected 'struct GStatBuf *' but argument
is of type 'struct _stati64 *'

https://bugzilla.gnome.org/show_bug.cgi?id=711547