obexd: Fix memory leak when loading plugins

On failure to open plugin directory, memory allocated to 'patterns'
and 'excludes' is not being freed, and the following memory leak is

Direct leak of 28 byte(s) in 1 object(s) allocated from:
    #0 0xb6aa1c49 in malloc (/usr/lib/liblsan.so+0x9c49)
    #1 0xb6976e89 in g_malloc (/lib/libglib-2.0.so.0+0x3ae89)
    #2 0xb69886f1 in g_strsplit_set (/lib/libglib-2.0.so.0+0x4c6f1)
    #3 0xb6f82f3b in plugin_init (/usr/libexec/bluetooth/obexd+0x20f3b)
    #4 0xb6f70dc9 in main (/usr/libexec/bluetooth/obexd+0xedc9)
1 file changed