Check for existence of pre-instaleld pst3 for Solaris tests in t/check_procs.t

plugins/t/check_procs.t

@@ -10,7 +10,7 @@ use NPTest;
 
 my $t;
 
-if (`uname -s` eq "SunOS\n") {
+if (`uname -s` eq "SunOS\n" && ! -x "/usr/local/nagios/libexec/pst3") {
 	plan skip_all => "Ignoring tests on solaris because of pst3";
 } else {
 	plan tests => 12;