clang complained that we may end up jumping
to the cleanup code without initializing data
in the jpeg code. Always initialize data to
NULL to prevent that eventuality.
Commit 59f6c50df8 set the memory limit to 100M,
which turns out to exclude some large, valid jpegs.
So, bump things to 300M, matching what was done
in gdk-pixbuf.
`free` is defined in `stdlib.h`, see for example
<https://pubs.opengroup.org/onlinepubs/009604499/functions/free.html>. Without
this include compilation can fail with the following error:
```
../gdk/loaders/gdkjpeg.c: In function ‘gdk_save_jpeg’:
../gdk/loaders/gdkjpeg.c:264:7: warning: implicit declaration of function ‘free’ [-Wimplicit-function-declaration]
free (data);
^
../gdk/loaders/gdkjpeg.c:264:7: warning: incompatible implicit declaration of built-in function ‘free’
../gdk/loaders/gdkjpeg.c:264:7: note: include ‘<stdlib.h>’ or provide a declaration of ‘free’
../gdk/loaders/gdkjpeg.c:302:67: error: ‘free’ undeclared (first use in this function)
return g_bytes_new_with_free_func (data, size, (GDestroyNotify) free, NULL);
^
../gdk/loaders/gdkjpeg.c:302:67: note: each undeclared identifier is reported only once for each function it appears in
../gdk/loaders/gdkjpeg.c:303:1: warning: control reaches end of non-void function [-Wreturn-type]
}
^
```
1. Change INSUFFICIENT_MEMORY to TOO_LARGE
GTK crashes on insufficient memory, we don't emit GErrors.
2. Split UNSUPPORTED into UNSUPPORTED_CONTENT and UNSUPPORTED_FORMAT
So we know if you need to find an RPM with a loader or curse and
the weird file.
3. Translate error messages, they are meant for end users.
