[llvm] [Offload] Fix the offload cache file triggering libc++ / libstdc++ mixing (PR #126313)

[Joseph Huber via llvm-commits]

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@@ -2,9 +2,6 @@ set(LLVM_ENABLE_PROJECTS "clang;clang-tools-extra;lld" CACHE STRING "")
 set(LLVM_ENABLE_RUNTIMES "compiler-rt;libunwind;libcxx;libcxxabi;openmp;offload" CACHE STRING "")
 set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR ON CACHE BOOL "")
 
-set(CLANG_DEFAULT_CXX_STDLIB "libc++" CACHE STRING "")
-set(CLANG_DEFAULT_LINKER "lld" CACHE STRING "")
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jhuber6 wrote:

It's not required for anything, probably shouldn't just default to it.

https://github.com/llvm/llvm-project/pull/126313