connection: Handle empty signature and signature with just a version.

Functions like wl_argument_from_va_list expect from get_next_argument,
to initialize details->type but when the signature is empty or contains
only version (like in desktop-shell-protocol.c in weston) it is left
uninitialized.

This patch fixes it, by initializing details->type with '\0' value,
signaling end of arguments.

Signed-off-by: Mariusz Ceier <mceier+wayland@gmail.com>
scanner: Fail more gracefully on out-of-memory

Failing with an error message and error code is little nicer.  I doubt we'll
hit this case much, but it makes the static analysis happy.
wayland-client: Handle potential NULL-deref

Instead, return -1 on out-of-memory.  errno will be set to ENOMEM by
the failing malloc.
Bump version to 1.2.0
protocol: Copy missing pixel formats from wl_drm to wl_shm
client: Simply wl_display_dispatch_queue_pending() and fix return value

We're supposed to return number of events dispatched on success, not 0.
Refactor to avoid goto and just return ret.
tests: do fixed test with random number more times

1000x in this case
tests: add some more list test

nothing big, just test if wl_list_empty() works
tests: simple interface_equal test
tests: Add some signal tests
tests: print backtrace when got SIGSEGV

the same way as in weston