ols: Always open serial port in nonblocking mode.

The scan() function was opening the port in non-blocking mode, the dev_open()
function however was not using the SERIAL_NONBLOCK flag. This led to hangs
in certain situations.

This fixes the OLS e.g. on NetBSD.
DT4000ZC/TP4000ZC: Force DTR=1 on the serial port.

This fixes the driver e.g. on NetBSD.
output/text: Fix memory leak of internal state buffers.

The text output module keeps buffers for internal state, upon receiving a DF_END
packet it frees the internal context but the buffers are never freed.

This adds a text_cleanup() helper function and registers it as the cleanup
function within all the text output modules.
Suppress compile warning
Update for libserialport v0.1 API.
gmc_mh_1x_2x: Inital driver skeleton.
serial: Allow 5 and 6 data bits.
Added SR_MQ_TIME and SR_MQFLAG_DURATION.
gmc_mh_1x_2x: Completed driver for Metrahit 1x/2x

This driver supports devices with “RS232“ interface (Metrahit 16I,
18S, Siemens B1105 tested, 29S incomplete).
Merge branch 'master' of https://github.com/Matthias-Heidbrink/libsigrok-mh

Conflicts:
	hardware/gmc-mh-1x-2x/protocol.h