Fix #34004: crash when canceling ongoing render with scene strip

Issue was caused by recursive call of RE_BlenderFrame. Solved by
reshuffling image pool init/free in do_render_all_options.

Should be harmless, but doublecheck on this is welcome.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54151 954f8c5b-7b00-dc11-b283-0030488c597c