This commit adds wildcard path matching. If path pattern given in
backend option ends with "*", it is considered as wildcard path. "*"
must match at least one character. All paths which include wildcard
path without last "*" as prefix, and are strictly longer than wildcard
path without last "*" are matched.
Suppose the wildcard patterns follows:
- *.nghttp2.org/foo
- *.img.nghttp2.org/bar
Previously, s.img.nghttp2.org/foo does not match anything. Now it
matches first pattern.