Disable erroneous warnings from clang

[thughes]

When building with clang, a few files are emitting warnings such as:

tests/subsys/usb/bos/src/test_bos.c:24:22: error: variable
'dummy_descriptor' is not needed and will not be emitted
[-Werror,-Wunneeded-internal-declaration]
static const uint8_t dummy_descriptor[] = {
                     ^

However, this variable is needed at compile-time since it's referenced
via sizeof(). This appears to be the same as this clang bug:
llvm/llvm-project#25458.

This warning only started being emitted when I re-enabled the
-Wunused-function warning for clang.

[thughes]

We could also just disable the -Wunneeded-internal-declaration warning, though that has the risk of disabling legitimate warnings. Example.

Since this warning occurs in so few places, I propose we just disable the few places we get erroneous warnings.

[mrodgers-witekio]

For the HTTP server test at least, I think the warning is genuine and we should probably verify that the response matches the expected string.

Adding:

zassert_mem_equal(buf, http1_header_capture_common_response, sizeof(http1_header_capture_common_response) - 1);

after test_read_data should fix it, I gave it a quick try and the tests all still pass.

[thughes]

Ah, thanks. I created #87585 to fix that. Let me know if you have ideas for the other tests.

[thughes]

Rather than disable the warnings, I created PRs to adjust the tests:

• tests: net: lib: http_server: Check response #87585
• tests: subsys: usb: bos: Remove dummy_descriptor struct #87591
• tests: mgmt: mcumgr: Disable clang warning #87592