Replaces GLib's g_str_has_prefix().

Allows big-endian users to configure the fallback byte order to
little-endian.  Without this setting, MPD assumes native byte order if
the CD drive can't decide.

Fixes a crash bug.  See code comment.

Migrate from the old curl_multi_perform() API to the newer
curl_multi_socket_action() API (since CURL 7.16).

This allows working around a bug with HTTP redirections with epoll:
when CURL closes a socket and the new one happens to have the same
file number, MPD did not have a chance to remove the old one from
epoll and subsequently attempted to use EPOLL_CTL_MOD, which was not
allowed by epoll, because it's a new socket now.

Move all global variables there, and keep just one global variable:
the pointer to the CurlMulti instance.  Prepares for the next commit.

Unused.

Eliminate some complicated code that's not worth the trouble.

Replaces the loop in input_curl_find_request().

Replaces GLib's g_ascii_strcasecmp().

Automatic memory management.

Decouple some more from GLib.

Replacing GLib macros.

Merge duplicate symbol.

This was a memory leak, because "mime" was a std::string which created
another copy and discarded the allocated buffer.

Micro-optimization.

Prepare to migrate away from GLib.  Currently, we're still using GLib
as a backend.

When playing finite http streams, e.g. something from soundcloud,
eventloop stalls after pausing writefunc. TimeoutMonitor is cancelled
by the time resume happens, so when enough data is consumed writefunc
is called only once. Calling InvalidateSockets() from
input_curl_resume() seems to fix the issue.

Use only ConfigData.hxx in plugin sources to reduce header
dependencies.