nmeter: simple code shrink here and there

nmeter: simple code shrink here and there

function                                             old     new   delta
nmeter_main                                          709     707      -2
init_cr                                               15      12      -3
collect_time                                         141     131     -10
collect_cpu                                          610     593     -17
init_cpu                                              82      63     -19
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/5 up/down: 0/-51)             Total: -51 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>