Fix unit tests

That was necessary with the two earlier reverts.

Author: gleu

check_pgactivity

@@ -49,6 +49,7 @@ use Pod::Usage;
 use Scalar::Util qw(looks_like_number);
 use Fcntl qw(:flock);
 use Storable qw(retrieve store);
+use Time::HiRes qw(gettimeofday tv_interval);
 
 use Config;
 use FindBin;

t/01-bgwriter.t

@@ -37,6 +37,8 @@ $node->command_checks_all( [
     'first basic check'
 );
 
+sleep 1;
+
 # Second check. Returns perfdata
 $node->command_checks_all( [
     './check_pgactivity', '--service'     => 'bgwriter',