hal/*/*/acq/sm_io_acq_exp.c: fix aligned number of samples

When acquiring data from the "acq" module, the number of
samples has to be multiple of 4 (for ADC channel) or 2
(for other channels). The previous calculation was wrong
as it didn't take into account for the alignment
number.

This fixes issue #10
libclient/*: fix handling of zctx_interrupted

Now, if the zctx_interrupted becomes active, a
BPM_CLIENT_INT error is issued and it exits the
current task properly
examples/*: fix handling of zctx_interrupted

The previous behavior still continued in the loop
but didn't executed anything. Now, if zctx_interrupted
becomes active the current loop exits appropriately