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

config/Rules.am

@@ -29,6 +29,7 @@ AM_CFLAGS += $(NO_OMIT_FRAME_POINTER)
 AM_CFLAGS += $(IMPLICIT_FALLTHROUGH)
 AM_CFLAGS += $(DEBUG_CFLAGS)
 AM_CFLAGS += $(ASAN_CFLAGS)
+AM_CFLAGS += $(UBSAN_CFLAGS)
 AM_CFLAGS += $(CODE_COVERAGE_CFLAGS) $(NO_FORMAT_ZERO_LENGTH)
 if BUILD_FREEBSD
 AM_CFLAGS += -fPIC -Werror -Wno-unknown-pragmas -Wno-enum-conversion
@@ -58,8 +59,17 @@ AM_CPPFLAGS += -D"__xpg_basename(...)=__xpg_basename(__VA_ARGS__) __attribute__(
 AM_CPPFLAGS += -D"basename(...)=basename(__VA_ARGS__) __attribute__((deprecated(\"basename(3) is underspecified. Use zfs_basename() instead!\")))"
 AM_CPPFLAGS += -D"dirname(...)=dirname(__VA_ARGS__) __attribute__((deprecated(\"dirname(3) is underspecified. Use zfs_dirnamelen() instead!\")))"
 
+if ASAN_ENABLED
+AM_CPPFLAGS += -DZFS_ASAN_ENABLED
+endif
+
+if UBSAN_ENABLED
+AM_CPPFLAGS += -DZFS_UBSAN_ENABLED
+endif
+
 AM_LDFLAGS  = $(DEBUG_LDFLAGS)
 AM_LDFLAGS += $(ASAN_LDFLAGS)
+AM_LDFLAGS += $(UBSAN_LDFLAGS)
 
 if BUILD_FREEBSD
 AM_LDFLAGS += -fstack-protector-strong -shared