[mod_alias] fix use-after-free bug (fixes #3114)
[mod_alias] fix use-after-free bug (fixes #3114)

(thx LoneFox)

bug introduced in 62a874df in lighttpd 1.4.59

x-ref:
  "Use-after-free bug in mod_alias"
  https://redmine.lighttpd.net/issues/3114

gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4