Fix gn android component build

R=jochen@chromium.org

Review URL: https://codereview.chromium.org/458423002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23592 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

BUILD.gn

@@ -1337,6 +1337,7 @@ component("v8") {
 
   direct_dependent_configs = [ ":external_config" ]
 
+  libs = []
   if (is_android && current_toolchain != host_toolchain) {
     libs += [ "log" ]
   }