Fix memory leak of error in ews_response_cb()
Fix memory leak of error in ews_response_cb()

==3576== 3,844 (944 direct, 2,900 indirect) bytes in 59 blocks are definitely lost in los
s record 24,613 of 25,597
==3576==    at 0x4A0649D: malloc (vg_replace_malloc.c:236)
==3576==    by 0x3D33049600: g_malloc (gmem.c:164)
==3576==    by 0x3D3305E476: g_slice_alloc (gslice.c:842)
==3576==    by 0x3D3302F1C1: g_error_new_valist (gerror.c:56)
==3576==    by 0x3D3302F50C: g_set_error (gerror.c:220)
==3576==    by 0x19923A82: ews_get_response_status (e-ews-connection.c:248)
==3576==    by 0x19923CAE: ews_response_cb (e-ews-connection.c:441)
==3576==    by 0x3D48043069: process_queue_item (soup-session-async.c:383)
==3576==    by 0x3D480432BF: run_queue (soup-session-async.c:418)
==3576==    by 0x3D48043912: idle_run_queue (soup-session-async.c:441)
==3576==    by 0x3D330427EC: g_main_context_dispatch (gmain.c:2441)
==3576==    by 0x3D33042FC7: g_main_context_iterate (gmain.c:3092)

GNOME/evolution-ews,GNOME/evolution-ews