[clang] [Clang][Driver] Skip empty strings in getAArch64MultilibFlags (PR #97827)

[Peter Smith via cfe-commits]

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@@ -0,0 +1,4 @@
+// RUN: %clang --target=aarch64-none-elf -march=armv8.9-a+rcpc3 -print-multi-flags-experimental -c %s 2>&1 | FileCheck %s
+
+// CHECK: -march=armv8.9-a
+// CHECK-SAME: +rcpc+rcpc3+
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smithp35 wrote:

I'm wondering if a `CHECK-NOT ++` could be used as well. This test might unexpectedly pass if the ordering of the features were changed. 

https://github.com/llvm/llvm-project/pull/97827