[compiler-rt] [compiler-rt] Use installed libc++(abi) for tests instead of build tree (PR #115077)

[Alexander Richardson via llvm-commits]

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@@ -680,15 +680,16 @@ macro(add_custom_libcxx name prefix)
 
   ExternalProject_Add(${name}
     DEPENDS ${name}-clobber ${LIBCXX_DEPS}
-    PREFIX ${CMAKE_CURRENT_BINARY_DIR}/${name}
+    PREFIX ${prefix}
     SOURCE_DIR ${LLVM_MAIN_SRC_DIR}/../runtimes
-    BINARY_DIR ${prefix}
+    BINARY_DIR ${prefix}/build
----------------
arichardson wrote:

Yes this is intentional - and the dependency for RTFuzzer is still there so I am not sure why it is failing for you:

```
    target_compile_options(RTfuzzer.${arch} PRIVATE -isystem ${LIBCXX_${arch}_PREFIX}/include/c++/v1)
    add_dependencies(RTfuzzer.${arch} libcxx_fuzzer_${arch}-install)
```

https://github.com/llvm/llvm-project/pull/115077