[monitoring-plugin-perl] Move Getopt param/reqd defs into dedicated hash

[Tom Ryder]

 Module: monitoring-plugin-perl
 Branch: master
 Commit: c1046bab2e6681f5e4714178d6cc1cd16f067382
 Author: Tom Ryder <tom at sanctum.geek.nz>
   Date: Sat Dec 16 13:02:34 2017 +1300
    URL: https://www.monitoring-plugins.org/repositories/monitoring-plugin-perl/commit/?id=c1046ba

Move Getopt param/reqd defs into dedicated hash

This shift and its comment makes what the values of the hashref passed
to the validate() methods mean clearer, and also allows the use of the
keys as a means of determining whether arg() was passed its definition
in the array or hash format in a separate commit.

---

 lib/Monitoring/Plugin/Getopt.pm | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/lib/Monitoring/Plugin/Getopt.pm b/lib/Monitoring/Plugin/Getopt.pm
index 262e3c8..ca1cb61 100644
--- a/lib/Monitoring/Plugin/Getopt.pm
+++ b/lib/Monitoring/Plugin/Getopt.pm
@@ -382,15 +382,18 @@ sub arg
   my $self = shift;
   my %args;
 
+  # Param name to required boolean
+  my %params = (
+      spec     => 1,
+      help     => 1,
+      default  => 0,
+      required => 0,
+      label    => 0,
+  );
+
   # Named args
   if ($_[0] =~ m/^(spec|help|required|default|label)$/ && scalar(@_) % 2 == 0) {
-    %args = validate( @_, {
-      spec => 1,
-      help => 1,
-      default => 0,
-      required => 0,
-      label => 0,
-    });
+    %args = validate( @_, { %params });
   }
 
   # Positional args