[mod_webdav] define _NETBSD_SOURCE on NetBSD
[mod_webdav] define _NETBSD_SOURCE on NetBSD

NetBSD dirent.h improperly hides fdopendir() (POSIX.1-2008) declaration
which should be visible w/ _XOPEN_SOURCE 700 or _POSIX_C_SOURCE 200809L

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