[stdlib][android] ignore the -Wgnu-offsetof-extensions in ExecutorChe…

[hyp]

…cks.cpp

ExecutorChecks.cpp no longer builds for android as -Wgnu -Werror is used for stdlib

[hyp]

@swift-ci please test

[ktoso]

Ok but what were the errors/warnings?

[compnerd]

This is rather unfortunate.

[hyp]

@ktoso these were the warnings:

D:/r/_work/swift-build/swift-build/SourceCache/swift/stdlib/public/Concurrency/ExecutorChecks.cpp:56:52: error: using an array subscript expression within 'offsetof' is a Clang extension [-Werror,-Wgnu-offsetof-extensions]
static_assert(offsetof(swift::Job, SchedulerPrivate[0]) == offsetof(SwiftJob, schedulerPrivate[0]));
                                                   ^
D:/r/_work/swift-build/swift-build/SourceCache/swift/stdlib/public/Concurrency/ExecutorChecks.cpp:56:95: error: using an array subscript expression within 'offsetof' is a Clang extension [-Werror,-Wgnu-offsetof-extensions]
static_assert(offsetof(swift::Job, SchedulerPrivate[0]) == offsetof(SwiftJob, schedulerPrivate[0]));
                                                                                              ^
D:/r/_work/swift-build/swift-build/SourceCache/swift/stdlib/public/Concurrency/ExecutorChecks.cpp:57:52: error: using an array subscript expression within 'offsetof' is a Clang extension [-Werror,-Wgnu-offsetof-extensions]
static_assert(offsetof(swift::Job, SchedulerPrivate[1]) == offsetof(SwiftJob, schedulerPrivate[1]));
                                                   ^
D:/r/_work/swift-build/swift-build/SourceCache/swift/stdlib/public/Concurrency/ExecutorChecks.cpp:57:95: error: using an array subscript expression within 'offsetof' is a Clang extension [-Werror,-Wgnu-offsetof-extensions]
static_assert(offsetof(swift::Job, SchedulerPrivate[1]) == offsetof(SwiftJob, schedulerPrivate[1]));

[hyp]

@swift-ci please test

[hyp]

@compnerd could you please kick off a windows build?

[hjyamauchi]

@swift-ci please test Windows Platform