Do not segfault when the font doesn't have a `/FamilyName` entry or `/FullName` 
in the `/FontInfo` dictionary.
Author: Stefan Dirsch <sndirsch@suse.com>
--- mkfontscale.c	2015-02-19 16:48:22.755393000 +0100
+++ mkfontscale.c	2015-02-19 16:55:00.043717000 +0100
@@ -579,11 +579,11 @@ 
     }
 
     if(t1info) {
-        if(!family)
+        if(!family && t1info->family_name)
             family = strdup(t1info->family_name);
-        if(!family)
+        if(!family && t1info->full_name)
             family = strdup(t1info->full_name);
-        if(!full_name)
+        if(!full_name && t1info->full_name)
             full_name = strdup(t1info->full_name);
         if(!foundry)
             foundry = notice_foundry(t1info->notice);