TODO: improve description.

- spawner.c: include the correct standard headers (errno.h, stdbool.h,
  string.h) instead of the unused dispatch/dlfcn headers, fixing
  implicit-declaration compile errors for bool/errno_t/strerror.
- Harness.UseSpawner: also reject a non-empty ArgumentList, and fail
  fast with a clear error if the spawner executable is missing.
- README.md: fix PID in the Electron example and correct a typo
  (reponsibility -> responsibility).

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 2f4c5e94-acb7-47c3-9555-8f952effb493

The spawner's Makefile relied on the generic per-RID compilation rules
from mk/rules.mk (.libs/osx-arm64/spawner.o etc.). Those rules are only
generated for the platforms that are enabled, via DOTNET_RUNTIME_IDENTIFIERS.

Most test jobs in CI run ./configure --disable-all-platforms --enable-<platform>
for a single non-macOS platform, which leaves INCLUDE_MAC empty. In that
configuration the osx-* RIDs don't exist, so no rule is generated for
.libs/osx-arm64/spawner.o and the build fails with:

    make: *** No rule to make target '.libs/osx-arm64/spawner.o',
    needed by '.libs/osx-arm64/spawner'.  Stop.

This is why the 'Generate / compile dependencies' step failed for the
ios/tvos/maccatalyst jobs but succeeded for the macos ones.

The spawner is a host tool that always runs on the macOS build machine and
is needed no matter which platforms are enabled, so define its own
compilation rules keyed off the architecture instead, and query the macOS
SDK path directly rather than using $(macos_SDK) (which is likewise only
meaningful when macOS is enabled).

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 2f4c5e94-acb7-47c3-9555-8f952effb493

The entire job's timeout is 3h.

… in CI.

Harness.GetIncludeSystemPermissionTests() had a switch over TestPlatform
that only handled iOS and Mac explicitly. Mac Catalyst fell through to
the 'default' branch, which assumes any non-device platform is a
simulator whose TCC database can be freely pre-seeded. Mac Catalyst
apps run natively on the host Mac (there's no Mac Catalyst simulator),
so that assumption doesn't hold, and DISABLE_SYSTEM_PERMISSION_TESTS
was never set for Mac Catalyst test runs.

This caused monotouch-test's Contacts.ContactStoreTest to run for
real (instead of being ignored), which hits a still-NotDetermined TCC
authorization status now that the new 'spawner' tool disclaims process
responsibility (so the child app is now checked on its own TCC status
instead of inheriting an already-approved responsible process). With
no interactive session available to answer the resulting system
permission dialog, the test process hangs until it's killed after the
20 minute timeout, exactly matching the CI hangs seen on
#24249 for the monotouch_maccatalyst
job (and by extension monotouch_macos, whose overall job timeout was
also exceeded as a result).

Add TestPlatform.MacCatalyst next to TestPlatform.Mac in the switch so
Mac Catalyst gets the same '!InCI' treatment as native macOS.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…ConverterTest.

CI run 15215315 (PR #24249) showed the exact same class of hang as the
previous fix (ccc70fb), just one test further down the alphabetical
list: after the Documents-directory write in
FileManagerTest.GetSkipBackupAttribute was fixed, macOS/Mac Catalyst
runs progressed further into Foundation.UrlTest, then hung again with
the same getxattr-on-main-thread signature right after
UrlTest.Invalid_29510 - i.e. at UrlTest.IsExcludedFromBackupKey, the
next test alphabetically.

IsExcludedFromBackupKey also writes a scratch file into the user's
Documents directory (NSSearchPathDirectory.DocumentDirectory) before
manipulating NSUrl.IsExcludedFromBackupKey on it. Now that tests run
through the new spawner tool (which disclaims process responsibility,
so the ephemeral test app is checked on its own TCC status instead of
inheriting an already-approved ancestor's), this write triggers a
fresh 'Files and Folders' authorization prompt that hangs forever with
no interactive session to answer it.

Fix it the same way as the previous commit: use
NSFileManager.TemporaryDirectory instead, which isn't behind a TCC
prompt and is already the established convention for scratch files
elsewhere in this test suite.

While auditing the rest of the test suite for the same anti-pattern (a
search for NSSearchPathDirectory.DocumentDirectory across
tests/monotouch-test), also fix
AudioConverterTest.ConvertWithPacketDependencies, which wrote its
output audio file into the Documents directory instead of using the
DoWithTemporaryDirectory helper that its sibling tests in the same
file (Convert, CreateWithOptions) already use for exactly this reason.
This wasn't yet confirmed as an observed CI hang (it likely wasn't
reached before the UrlTest hang), but it has the identical risk and
would very likely have been the next hang once UrlTest was fixed.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: ca98fc3c-135b-4bad-80dc-50262be55c90