[PATCH] At-exit leaks

Hello,

    The attached patch Various at-exit-time leaks removed to minimize
valgrind false positives.

Removing these leaks helps with detecting true leaks, but it is possible
that these changes expose other bugs that crash exiting Squid. We have
not seen such crashes in our limited tests.

Some of this cleanup code used to be enabled in LEAK_CHECK_MODE but then
the whole cleanup code was marked as "broken" in 2006:

  #if LEAK_CHECK_MODE && 0 /* doesn't work at the moment */

It is possible that the parts of the cleanup code that this patch
re-enables is not broken, but I do not really know that.

Needless to say, at-exit leaks themselves are harmless because the OS is
going to reclaim all process memory after the process exits. However,
besides misleading valgrind, some (future?) cleanup code enabled by
these changes might affect on-disk or shared memory state.

These possible cleanup actions (that may be difficult to track reliably)
make re-enabling LEAK_CHECK_MODE conditional for this code not such a
good idea. Besides, if we do not enable the cleanup on a permanent
basis, the usually unused code may never work correctly.

Still, at-exit crashes are annoying and this patch might introduce them.

I am not quite sure whether this patch should be committed, but will
probably commit it if there are no other opinions.

Thank you,

Alex.