Fix invocation of groff 1.22.3 to pass on -P-c

Because, without that argument, groff (invoking grotty) will output
SGR escape sequences, which we're not ready to deal with.

lib/ManUtils/ManUtils.pm

@@ -67,6 +67,9 @@ sub fmt {
       push @$errors, "grog detected several macro packages: $double. Using $macros. (@cmd)";
     }
 
+    # grog 1.22.3 somehow loses the -P-c argument, let's make sure it's in the list.
+    splice @cmd, 1, 0, '-P-c';
+
     my $groff = run_cmd \@cmd,
       '<' => \$input,
       '>' => \my $fmt,