[obexd] Close pipe fds after get capability object. Fixes JB#13818.

g_spawn_async_with_pipes() will create child process and two pipe
for output and err. Each pipe have two ends. One for child
process(write), one for parent process(read).
Parent process(obexd) should close the pipe which belongs to his
end after used it.
Merge pull request #1 from tmioss/FTP-fix-close-pipe-fds-issue

[obexd] Close pipe fds after get capability object. Fixes JB#13818.