make sure configure fails if AC_CHECK_ALIGNOF cannot detect the alignment

When cross-compiling with gcc >= 4.5 AC_CHECK_ALIGNOF fails to detect the
correct alignment. Without a previous AC_CHECK_TYPE for the same type, the
alignment is silently set to '0'.
This makes sure that configure fails and reports the problem.

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>

https://bugzilla.gnome.org/show_bug.cgi?id=674483
gsocket: test if family is <= 0, not < 0

If all members of GSocketFamily are supported on the platform, then
all of its values will be positive, and so the enum might become
unsigned, in which case testing for "family < 0" might cause warnings.
But we want to return an error if family == 0 (aka
G_SOCKET_FAMILY_INVALID) anyway, so just tweak the test accordingly.

https://bugzilla.gnome.org/show_bug.cgi?id=674592
build: Fix 'make dist' regression

Commit f084b603771f78126bc0b07229a1574b76e776bb incorrectly set
DIST_SUBDIRS for the toplevel Makefile.am.  In general actually we
don't need to set it, because modern automake automatically sets
it by looking at conditionals for SUBDIRS.

Tested-by: Rico Tzschichholz <ricotz@t-online.de>

https://bugzilla.gnome.org/show_bug.cgi?id=667806
Dist gio/dbus-daemon.xml and fix dependency for builddir != srcdir
Updated Hebrew translation.
GAppInfo: overwrite the DISPLAY only if it is set in the launch context

If the launch context is a GAppLaunchContext, and not a
GdkAppLaunchContext, then g_app_launch_context_get_display will return
NULL because the get_display virtual method is undefined. The DISPLAY
might still be inherited from the parent process, in which case
overwriting it with NULL breaks the launch.

This is a regression introduced in:
de834bed306565c0652050665eafff4dfcdf0d8b

Fixes: https://bugzilla.gnome.org/672786
Add g_clear_pointer()

Also reimplement g_clear_object() using g_clear_pointer()

https://bugzilla.gnome.org/show_bug.cgi?id=674634
Fix several recently-introduced bugs in g_output_stream_write_async()

g_output_stream_write_async() was not initializing the newly-added
members of the WriteData structure, causing various problems.

Also, g_input_stream_read_async() was now leaking its cancellable. Fix
that as well.

https://bugzilla.gnome.org/show_bug.cgi?id=674612
Updated Brazilian Portuguese translation
Updated Norwegian bokmål translation
fix warnings
Update gio/tests/.gitignore
l10n: Updated Italian translation
Updated Galician translations
g_clear_pointer: use the same static checks than g_clear_object in glib-2-32
Updated French translation
GApplication: allow null application_id

GApplication application ID is now permitted to be NULL, in which case
G_APPLICATION_NON_UNIQUE will be implicitly enabled.

https://bugzilla.gnome.org/show_bug.cgi?id=671249
GApplication: add accessor for DBus information

Provide public access to the GDBusConnect and object path that
GApplication is using.  Prevents others from having to guess these
things for themselves based on the application ID.

https://bugzilla.gnome.org/show_bug.cgi?id=671249
configure: Reset LIBS after ELF check

If action-if-found is not specified, AC_CHECK_LIB will append the library
to LIBS. As we don't want to link everything against libelf, reset LIBS
after doing the checks.
contenttype test: don't pass -1 as length

g_content_type_guess() takes a gsize, not a gssize, and -1 does not mean
"I am passing a NULL terminated string".