[clang] [LTO] Fix Veclib flags correctly pass to LTO flags (PR #78749)

[Paschalis Mpeis via cfe-commits]

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@@ -31,3 +31,27 @@
 
 // RUN: %clang -fveclib=Accelerate %s -nodefaultlibs -target arm64-apple-ios8.0.0 -### 2>&1 | FileCheck --check-prefix=CHECK-LINK-NODEFAULTLIBS %s
 // CHECK-LINK-NODEFAULTLIBS-NOT: "-framework" "Accelerate"
+
+
+/* Verify that the correct vector library is passed to LTO flags. */
+
+// RUN: %clang -### -fveclib=Accelerate -flto %s -v 2>&1 | FileCheck -check-prefix CHECK-LTO-ACCELERATE %s
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paschalis-mpeis wrote:

Actually it turns out that some of the veclibs (like Accelerate in this case) do not have any target/toolchain that would call `addLTOOptions`. So I removed those.

The ones that remain, all specify a target.

https://github.com/llvm/llvm-project/pull/78749