Add --enable-asan and --enable-ubsan switches

`configure` now accepts `--enable-asan` and `--enable-ubsan` switches
which results in passing `-fsanitize=address`
and `-fsanitize=undefined`, respectively, to the compiler. Those
flags are enabled in GitHub workflows for ZTS and zloop. Errors
reported by both instrumentations are corrected, except for:

- Memory leak reporting is (temporarily) suppressed. The cost of
  fixing them is relatively high compared to the gains.

- Checksum computing functions in `module/zcommon/zfs_fletcher*`
  have UBSan errors suppressed. It is completely impractical
  to enforce 64-byte payload alignment there due to performance
  impact.

- There's no ASan heap poisoning in `module/zstd/lib/zstd.c`. A custom
  memory allocator is used there rendering that measure
  unfeasible.

- Memory leaks detection has to be suppressed for `cmd/zvol_id`.
  `zvol_id` is run by udev with the help of `ptrace(2)`. Tracing is
  incompatible with memory leaks detection.

Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: szubersk <szuberskidamian@gmail.com>
Closes #12928

scripts/zloop.sh

@@ -215,7 +215,8 @@ shift $((OPTIND - 1))
 
 # enable core dumps
 ulimit -c unlimited
-export ASAN_OPTIONS=abort_on_error=1:disable_coredump=0
+export ASAN_OPTIONS=abort_on_error=true:halt_on_error=true:allocator_may_return_null=true:disable_coredump=false:detect_stack_use_after_return=true
+export UBSAN_OPTIONS=abort_on_error=true:halt_on_error=true:print_stacktrace=true
 
 if [[ -f "$(core_file)" ]]; then
 	echo -n "There's a core dump here you might want to look at first... "