[libc++][test] Use ADDITIONAL_COMPILE_FLAGS(gcc-style-warnings) for -Wno-psabi (#113608)

MSVC doesn't understand `-Wno-psabi`, which was introduced here by
@ldionne in #106077.

Using `ADDITIONAL_COMPILE_FLAGS(gcc-style-warnings)` (implemented by
#75317) avoids passing this to MSVC.

Author: StephanTLavavej

libcxx/test/std/atomics/atomics.lockfree/is_always_lock_free.pass.cpp

@@ -18,7 +18,7 @@
 
 // Ignore diagnostic about vector types changing the ABI on some targets, since
 // that is irrelevant for this test.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-psabi
+// ADDITIONAL_COMPILE_FLAGS(gcc-style-warnings): -Wno-psabi
 
 #include <atomic>
 #include <cassert>