mingw-w64: fix build with Xcode 15.3

[mrpippy]

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---

Backport two GCC patches (by @fxcoudert) that fix building from source with Xcode 15.3. (#167872 is failing because of them).

[mrpippy]

Rebased to see if the spurious CI failure resolves itself

[github-actions]

🤖 An automated task has requested bottles to be published to this PR.

[adfoster-r7]

Hi there; I appear to be getting this issue locally - just wanted to confirm if that sha is correct 👀

==> Downloading https://gcc.gnu.org/git/?p=gcc.git;a=patch;h=9970b576b7e4ae337af1268395ff221348c4b34a
Already downloaded: /Users/vagrant/Library/Caches/Homebrew/downloads/6c68aa4aef135895a658b1ab6d97313af8eadb8add341ff7a61b747317d00608--gcc.git-9970b576b7e4ae337af1268395ff221348c4b34a.patch
Error: mingw-w64: SHA256 mismatch
Expected: 968bfcb58f75d889470f2f815787f6aa254fb43f1e5516e04f577dad22259905
  Actual: 7f79e6bf59d58562990baaed5a69f83df57e6d6255a3ddf5c779320e58dd5f30
    File: /Users/vagrant/Library/Caches/Homebrew/downloads/6c68aa4aef135895a658b1ab6d97313af8eadb8add341ff7a61b747317d00608--gcc.git-9970b576b7e4ae337af1268395ff221348c4b34a.patch
To retry an incomplete download, remove the file above.

Also verified via the host:

$ curl -s https://gcc.gnu.org/git/\?p\=gcc.git\;a\=patch\;h\=9970b576b7e4ae337af1268395ff221348c4b34a | sha256sum
7f79e6bf59d58562990baaed5a69f83df57e6d6255a3ddf5c779320e58dd5f30  -