Don't leak the GFile.

==2493== 46 (16 direct, 30 indirect) bytes in 1 blocks are definitely lost in loss record 579 of 921
==2493==    at 0x402AD89: malloc (vg_replace_malloc.c:236)
==2493==    by 0x45772DA: standard_malloc (gmem.c:85)
==2493==    by 0x4577680: g_malloc (gmem.c:159)
==2493==    by 0x458B29D: g_slice_alloc (gslice.c:1003)
==2493==    by 0x458B805: g_slice_alloc0 (gslice.c:1029)
==2493==    by 0x426DBA7: g_type_create_instance (gtype.c:1872)
==2493==    by 0x4250717: g_object_constructor (gobject.c:1839)
==2493==    by 0x4252488: g_object_newv (gobject.c:1622)
==2493==    by 0x4252A17: g_object_new (gobject.c:1532)
==2493==    by 0x4176D3A: _g_local_file_new (glocalfile.c:288)
==2493==    by 0x417EA84: g_local_vfs_get_file_for_uri (glocalvfs.c:110)
==2493==    by 0x410E8DB: g_vfs_get_file_for_uri (gvfs.c:130)
==2493==    by 0x40C93DE: g_file_new_for_uri (gfile.c:5893)
==2493==    by 0x403A59F: _rsvg_io_acquire_data (rsvg-io.c:265)