The glib GTimeVal data type (and some functions using it) will be faded
out from glib sooner or later, so it's not a good idea to use them anyway.
In this specific case GTimeVal.tv_sec was overflowing, leading a check in
libsigrok to fail, and thus to FX2 firmware upload errors, i.e.
non-working fx2lafw devices.
http://thread.gmane.org/gmane.comp.debugging.sigrok.devel/166
The root cause is that GTimeVal.tv_sec is a 'glong' (8 bytes on 64bit
systems, but only 4 on 32bit systems).
We now use an int64_t (and g_get_monotonic_time() instead of the more
problematics g_get_current_time() which uses a GTimeVal).
This has been verified to fix the issue on a 32bit system.
Other uses of GTimeVal in libsigrok will be removed in a later release.
Also, drop unneeded GTV_TO_MSEC.
Start/stop acquisition callbacks: Consistently name the 'void *' parameter
cb_data for now. The per-device-instance device pointer is called
'session_dev_id' everywhere for now, but this should be renamed to
something more clear.
Uwe Hermann
Joel Holdsworth