It causes trouble at least for (non-debug) 32-bit ARM Flatpak builds, where
CppunitTest_vcl_filters_test aborts with an uncaught css::uno::RuntimeException.

This is a partial revert of 6889fa82 "rework
jpeg error handling to throw rather than setjmp to avoid leaks", switching back
to setjmp/longjmp but trying to keep the leaks fixed by introducing any relevant
local variables before the setjmps.

Change-Id: Ia5984528ea98be1c89a21aee800b247120f88a89
Reviewed-on: https://gerrit.libreoffice.org/43494Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>