x86: increase timeout in qemu's term

Currently `boards/qemu-i386/dist/term.py` expects QEMU to connect in
less than 5 seconds, which is plenty on any user machine. Travis CI,
which we use without paying a cent, sometimes fails to start QEMU in
this is timeframe, though.

This PR increases the timeout to one minute.
Merge pull request #1382 from Kijewski/qemu-i86-term-timeout

x86: increase timeout in qemu's term