[llvm] [clang-tools-extra] [flang] [Flang] make ppc unsupported for x86_64 test case (NFC) (PR #73903)

[Kelvin Li via cfe-commits]

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@@ -7,7 +7,7 @@
 !
 ! This test is for x86_64, where exponent-letter 'q' is for
 ! 10-byte extended precision
-! UNSUPPORTED: system-windows
+! UNSUPPORTED: system-windows, system-aix
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kkwli wrote:

Why not `target=powerpc{{.*}}` as PPC is non-x86_64 regardless of the OS?

https://github.com/llvm/llvm-project/pull/73903