scripts/metadata.pm: avoid adding dup names in provides list

The need arises from building Open vSwitch kernel datapath modules, e.g.

 - kmod-openvswitch from Linux upstream
 - kmod-openvswitch-intree from openvswitch source code

where both provides virtual package "kmod-openvswitch" for userspace
packages to select and depend on

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

scripts/metadata.pm

@@ -250,6 +250,7 @@ sub parse_package_metadata($) {
 			my @vpkg = split /\s+/, $1;
 			@{$pkg->{provides}} = ($pkg->{name}, @vpkg);
 			foreach my $vpkg (@vpkg) {
+				next if ($vpkg eq $pkg->{name});
 				$vpackage{$vpkg} or $vpackage{$vpkg} = [];
 				push @{$vpackage{$vpkg}}, $pkg;
 			}