Fix use of uninitialized value $config{"options"}

When no options are specified for a deb line in the config (e.g. no
[arch=amd64] or similar), apt-mirror will print a warning:

Use of uninitialized value $config{"options"} in pattern match (m//) at
apt-mirror line 300, <CONFIG> line 6.

fixes #68

1 files changed, 1 insertions, 1 deletions

diff --git a/apt-mirror b/apt-mirror
index 7d9ff5c..ec2b09d 100755
--- a/apt-mirror
+++ b/apt-mirror
@@ -294,7 +294,7 @@ sub parse_config_line
     if ( $line =~ $pattern_deb_line ) {
         $config{'type'} = $+{type};
         $config{'arch'} = $+{arch};
-        $config{'options'} = $+{options};
+        $config{'options'} = $+{options} ? $+{options} : "";
         $config{'uri'} = $+{uri};
         $config{'components'} = $+{components};
         if ( $config{'options'} =~ /arch=((?<arch>[\w\-]+)[,]*)/g ) {