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

cmd/ztest/ztest.c

@@ -631,6 +631,8 @@ fatal(int do_perror, char *message, ...)
 
 	(void) fflush(stdout);
 	buf = umem_alloc(FATAL_MSG_SZ, UMEM_NOFAIL);
+	if (buf == NULL)
+		goto out;
 
 	va_start(args, message);
 	(void) sprintf(buf, "ztest: ");
@@ -644,6 +646,7 @@ fatal(int do_perror, char *message, ...)
 	(void) fprintf(stderr, "%s\n", buf);
 	fatal_msg = buf;			/* to ease debugging */
 
+out:
 	if (ztest_dump_core)
 		abort();
 	else