osc: g_thread_init is deprecated since 2.32

The GLib threading system gets automatically initialized at program
start.

Signed-off-by: Tim Harder <timothy.harder@analog.com>
osc: minor whitespace consistency

Signed-off-by: Tim Harder <timothy.harder@analog.com>
plugins/datafile_in.h: use proper data type for complex numbers

This fixes "dereferencing pointer to incomplete type" compile errors.

Signed-off-by: Tim Harder <timothy.harder@analog.com>