[private] Free the font name after setting it
[private] Free the font name after setting it

==11460== 55,067 (19,575 direct, 35,492 indirect) bytes in 950 blocks are
definitely lost in loss record 312 of 341
==11460==    at 0x4C2391E: malloc (vg_replace_malloc.c:207)
==11460==    by 0xB6A7552: g_malloc (gmem.c:131)
==11460==    by 0xB6BF01D: g_strdup (gstrfuncs.c:102)
==11460==    by 0xB24EB5C: value_lcopy_string (gvaluetypes.c:313)
==11460==    by 0x704913A: mx_style_get_valist (mx-style.c:418)
==11460==    by 0x7047CE3: mx_stylable_get (mx-stylable.c:515)
==11460==    by 0x7058756: _mx_widget_set_clutter_text_attributes
(mx-private.c:125)
==11460==    by 0xB2293EC: g_closure_invoke (gclosure.c:767)
==11460==    by 0xB23CCDA: signal_emit_unlocked_R (gsignal.c:3247)
==11460==    by 0xB23E081: g_signal_emit_valist (gsignal.c:2980)
==11460==    by 0xB23E3B9: g_signal_emit_by_name (gsignal.c:3074)
==11460==    by 0x7056A5A: mx_widget_stylable_changed (mx-widget.c:613)

clutter-project/mx,pwithnall/mx,jonnylamb/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx,clutter-project/mx,jonnylamb/mx,pwithnall/mx,jonnylamb/mx