Remove smart match and lexical $_ for compatibility with perl 5.18. #1216

lib/Slic3r/Config.pm

@@ -1141,7 +1141,7 @@ sub set {
     my ($opt_key, $value, $deserialize) = @_;
     
     # handle legacy options
-    return if $opt_key ~~ @Ignore;
+    return if first { $_ eq $opt_key } @Ignore;
     if ($opt_key =~ /^(extrusion_width|bottom_layer_speed|first_layer_height)_ratio$/) {
         $opt_key = $1;
         $opt_key =~ s/^bottom_layer_speed$/first_layer_speed/;
@@ -1413,7 +1413,7 @@ sub read_ini {
     
     my $ini = { _ => {} };
     my $category = '_';
-    while (my $_ = <$fh>) {
+    while (<$fh>) {
         s/\R+$//;
         next if /^\s+/;
         next if /^$/;

lib/Slic3r/Format/OBJ.pm

@@ -8,7 +8,7 @@ sub read_file {
     Slic3r::open(\my $fh, '<', $file) or die "Failed to open $file\n";
     my $vertices = [];
     my $facets = [];
-    while (my $_ = <$fh>) {
+    while (<$fh>) {
         if (/^v ([^ ]+)\s+([^ ]+)\s+([^ ]+)/) {
             push @$vertices, [$1, $2, $3];
         } elsif (/^f (\d+).*? (\d+).*? (\d+).*?/) {

lib/Slic3r/Format/STL.pm

@@ -53,7 +53,7 @@ sub _read_ascii {
     my $facet;
     my %vertices_map = ();
     seek $fh, 0, 0;
-    while (my $_ = <$fh>) {
+    while (<$fh>) {
         if (!$facet) {
             /^\s*facet\s+normal\s+/ or next;
             $facet = [];  # ignore normal
@@ -88,7 +88,7 @@ sub _read_binary {
     my %vertices_map = ();
     binmode $fh;
     seek $fh, 80 + 4, 0;
-    while (read $fh, my $_, 4*4*3+2) {
+    while (read $fh, $_, 4*4*3+2) {
         push @$facets, my $facet = [];
         for (unpack 'x[f3](a[f3])3') {  # ignore normal
             my $vertex_idx;