[mod_webdav] lseek,read if fs can not mmap (#2666, fixes #962)
[mod_webdav] lseek,read if fs can not mmap (#2666, fixes #962)

For uploaded files or other request body, fall back to
lseek(),read() if filesystem does not support mmap()

(mmap(), if supported, is utilized regardless of --enable-mmap
 since request body is either in memory or stored in temporary
 files controlled by lighttpd)

x-ref:
  "WebDAV upload-> mmap failed: operation not permitted"
  https://redmine.lighttpd.net/issues/962
  "handle filesystems without mmap() support"
  https://redmine.lighttpd.net/issues/2666

github: closes #55

PatchyFog/lighttpd1.4-mbedtls,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,PatchyFog/lighttpd1.4-mbedtls,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,PatchyFog/lighttpd1.4-mbedtls,PatchyFog/lighttpd1.4-mbedtls,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,PatchyFog/lighttpd1.4-mbedtls,PatchyFog/lighttpd1.4-mbedtls,gstrauss/lighttpd1.4,PatchyFog/lighttpd1.4-mbedtls,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4