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/zfs-tests.sh

@@ -148,7 +148,7 @@ trap cleanup EXIT
 # be dangerous and should only be used in a dedicated test environment.
 #
 cleanup_all() {
-	TEST_POOLS=$(sudo "$ZPOOL" list -H -o name | grep testpool)
+	TEST_POOLS=$(sudo env ASAN_OPTIONS=detect_leaks=false "$ZPOOL" list -H -o name | grep testpool)
 	if [ "$UNAME" = "FreeBSD" ] ; then
 		TEST_LOOPBACKS=$(sudo "${LOSETUP}" -l)
 	else
@@ -160,7 +160,7 @@ cleanup_all() {
 	msg "--- Cleanup ---"
 	msg "Removing pool(s):     $(echo "${TEST_POOLS}" | tr '\n' ' ')"
 	for TEST_POOL in $TEST_POOLS; do
-		sudo "$ZPOOL" destroy "${TEST_POOL}"
+		sudo env ASAN_OPTIONS=detect_leaks=false "$ZPOOL" destroy "${TEST_POOL}"
 	done
 
 	if [ "$UNAME" != "FreeBSD" ] ; then
@@ -554,7 +554,7 @@ fi
 # space-delimited to newline-delimited.
 #
 if [ -z "${KEEP}" ]; then
-	KEEP="$(sudo "$ZPOOL" list -H -o name)"
+	KEEP="$(sudo env ASAN_OPTIONS=detect_leaks=false "$ZPOOL" list -H -o name)"
 	if [ -z "${KEEP}" ]; then
 		KEEP="rpool"
 	fi