fuzz: build without AddressSanitizer, by default

fuzz: build without AddressSanitizer, by default

We already have a nice --enable-sanitizers option to enable
AddressSanitizer. There is no reason to duplicate and force this
functionality in --enable-fuzzing. In the future, if more sanitizers are
added to --enable-sanitizers, it might be impossible to build with both
--enable-sanitizers and --enable-fuzzing, since not all sanitizers are
compatible with libFuzzer. In that case, we could enable ASAN with
--extra-cflags="-fsanitize=address"

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20200706195534.14962-2-alxndr@bu.edu>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
[thuth: Added missing $CFLAGS]
Signed-off-by: Thomas Huth <thuth@redhat.com>