pdf: support JBIG2 mime data

JBIG2 images may have shared global data that is stored in a separate
stream in PDF. The CAIRO_MIME_TYPE_JBIG2 mime type is for the JBIG2
data for each image. All images that use global data must also set
CAIRO_MIME_TYPE_JBIG2_GLOBAL_ID to a unique identifier. One of the
images must also set CAIRO_MIME_TYPE_JBIG2_GLOBAL to the global
data. The global data will be shared by all JBIG2 images with the same
CAIRO_MIME_TYPE_JBIG2_GLOBAL_ID.
test: update mime-data to test jbig2 mime types
cairo-gobject: Require at least glib 2.14

cairo-gobject uses g_once_init_enter() and g_once_init_leave(). These functions
were added in glib 2.14 and thus cairo needs at least this version for its
gobject helper functions.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=69239
Signed-off-by: Uli Schlachter <psychon@znc.in>
check-doc-syntax: Don't hardcode path to awk

Instead of expecting awk in /usr/bin, this commit changes the code to call awk
through a shell so that $PATH is searched.

Since this awk script shouldn't really be called manually, this is done by
removing the shebang from the awk script, marking it non-executable and fixing
up the caller.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67674
Reviewed-by: Bryce Harrington <b.harrington@samsung.com>
Signed-off-by: Uli Schlachter <psychon@znc.in>
image: Handle PIXMAN_a8r8g8b8_sRGB in switch

Fixes the following compiler warning:

cairo-image-surface.c: In function '_cairo_format_from_pixman_format':
cairo-image-surface.c:93: warning: enumeration value 'PIXMAN_a8r8g8b8_sRGB' not
handled in switch

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=58726
Signed-off-by: Uli Schlachter <psychon@znc.in>
test/multi-page: Fix use-after-free

Commit f9dcd07d22a5269 changed the way the file name is allocated and introduced
a use-after-free in doing so.

Signed-off-by: Uli Schlachter <psychon@znc.in>
xcb: Remove useless error handling

All the *_reply() functions in XCB return a pointer to their result and as last
argument they get a xcb_generic_error_t** where pointers to errors are stored,
if any occurs.

However, a request can either fail or succeed. This means that if the returned
result is a NULL pointer, then an error occurred and the other way around: If
the error pointer is set to non-NULL, then the function must have returned NULL.

Thus, all the code, which just checks if an error occurred and which does not
care about the exact error code, does not need to get the error pointer at all.
In this case, xcb will free() the error internally.

While doing this, I noticed that _cairo_xcb_connection_get_image() always
succeeds and thus its return value can be replaced with the GetImage result.

Signed-off-by: Uli Schlachter <psychon@znc.in>