fix boost (#5000)

packages/b/boost/xmake.lua

@@ -282,16 +282,19 @@ package("boost")
             local info = dep:fetch({external = false})
             if info then
                 local includedirs = table.wrap(info.sysincludedirs or info.includedirs)
-                    if #includedirs != 0 then
                 for i, dir in ipairs(includedirs) do
                     includedirs[i] = path.unix(dir)
                 end
+                local linkdirs = table.wrap(info.linkdirs)
+                for i, dir in ipairs(linkdirs) do
+                    linkdirs[i] = path.unix(dir)
                 end
+                local links = table.wrap(info.links)
                 local usingstr = format("\nusing %s : %s : <include>%s <search>%s <name>%s ;",
                     rule, dep:version(),
                     table.concat(includedirs, ";"),
-                        path.unix(info.linkdirs[1]),
-                        info.links[1])
+                    table.concat(linkdirs, ";"),
+                    table.concat(links, ";"))
                 file:write(usingstr)
             end
         end