Fix a mistake with the build where certain header files (sha1.h and sha2.h) needed to be included portably.

Remove sha{1,2}.h from source files as these are included portably.

A folder parameter addressing the root directory is expected to be an empty string rather than "/".

ok op@

Fields of the querystring structure become fixed-sized buffers for easy passing over imsg. This means we can no longer check pointers in this structure for NULL. Instead we have to check for empty strings. ok op@

Instead of distributing requests across workers in a round-robin fashion keep track of how many requests a given worker has queued and send new requests to the worker which has the least amount of work queued for it. This makes gotwebd much more responsive than stupid round-robin, even though the new strategy is still not optimal because different types of requests carry different cost. E.g. blaming a file is usually heavier than listing trees. But it might be good enough, for now. Let's try and see. ok op@

The listen statement is a global configuration setting and it does not make sense to have more than one process listening. Run just one process which listens and is now again called "sockets", having been renamed from "sockets" to "server" some time ago. There is no good reason to run more than one "server" since server-specific settings from gotwebd.conf are selected based on the SERVER_NAME sent in the FastCGI request. This selection is handled by the gotweb.c process. ok op@

* clean up the SOCKS_BACKLOG versus SOMAXCONN usage * factor out just one listen() call * slightly improve the logging by showing the socket "name" too. ok stsp@