[llvm] [llvm] Disable some LLVM arguments in runtimes mode (PR #73031)

[Louis Dionne via llvm-commits]

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@@ -151,6 +151,9 @@ endif()
 # Avoid checking whether the compiler is working.
 set(LLVM_COMPILER_CHECKED ON)
 
+# This can be used to detect whether we're in the runtimes build.
+set(LLVM_RUNTIMES_BUILD ON)
+
 # Handle common options used by all runtimes.
 include(AddLLVM)
 include(HandleLLVMOptions)
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ldionne wrote:

I actually don't know what we're picking up from `HandleLLVMOptions` but it all sounds like just dangerous to do in the context of the runtimes build. A naive build locally seems to work if we remove `include(HandleLLVMOptions)` entirely -- this is what I would try doing instead.

@petrhosek might know more.

https://github.com/llvm/llvm-project/pull/73031