safer -i option parsing

ci/test-12-option-type.pl

@@ -1,8 +1,8 @@
 #!/usr/bin/perl -w
 
-use Test::Command tests => 30;
+use Test::Command tests => 33;
 
-for my $arg (qw(b B c C H O p Q r t)) {
+for my $arg (qw(b B c C H i O p Q r t)) {
     my $cmd = Test::Command->new(cmd => "fping -$arg xxx");
     $cmd->exit_is_num(1);
     $cmd->stdout_is_eq("");

src/fping.c

@@ -400,12 +400,14 @@ int main( int argc, char **argv )
             break;
         
         case 'r':
-            if (!sscanf(optarg,"%i",&retry))
+            if (!sscanf(optarg,"%u",&retry))
                 usage(1);
             break;
         
         case 'i':
-            interval = ( unsigned int )atoi( optarg ) * 100;
+            if (!sscanf(optarg,"%u",&interval))
+                usage(1);
+            interval *= 100;
             break;
 
         case 'p':