build: Install wayland-scanner.mk under $(pkgdatadir).
build: Add wayland-scanner.pc.

To allow user program to include wayland-scanner.m4 in tarball, move
the path variables from it into wayland-scanner.pc.
wayland-server: Add wl_global_create/destroy()

This patch introduces wl_global_create() and wl_global_destroy() as
replacements for wl_display_add_global() and wl_display_remove_global().
The add/remove_global API did not allow a compositor to indicate
the implemented version of a global, it just took the version from
the interface meta data.  The problem is that the meta data
(which lives in libwayland-server.so) can get out of sync with a
compositor implementation.  The compositor will then advertise a
higher version of a global than what it actually implements.

The new API lets a compositor pass in a version when it registers
a global, which solves the problem.  The add/remove API is deprecated
with this patch and will be removed.
wayland-client: Treat EOF when reading the wayland socket as an error

If EOF is encountered while reading from the Wayland socket, make
wl_display_read_events() return -1 so that it will be treated as an
error. The documentation for this function states that it will set
errno when there is an error so it additionally makes up an errno of
EPIPE.

If we don't do this then when the compositor quits the Wayland socket
will be become ready for reading but wl_display_dispatch will do
nothing which typically makes the application take up 100% CPU. In
particular eglSwapBuffers will likely get stuck in an infinite busy
loop because it repeatedly calls wl_display_dispatch_queue while it
waits for the frame callback.

https://bugzilla.gnome.org/show_bug.cgi?id=703892
wayland-server: Return 0 from read_events() in case of EAGAIN

Getting no data from the socket is not an error condition.  This may
happen in case of calling prepare_read() and then read_events() with
no other pending readers and no data in the socket.  In general,
read_events() may not queue up events in the given event queue.  From
a given threads point of view it doesn't matter whether events were
read and put in a different event queue or no events were read at all.
wayland-server: Don't close display fd in fatal error handler

We can't do that there, we have to make sure it stays a valid fd until
the application calls wl_display_disconnect().  Otherwise the application
may end up poll()ing on a stale or wrong fd in case another part of the
application (or another thread) triggered a fatal error.
Replace two remaining wl_display_add_gloavl() occurences
Bump version to 1.1.91