Revert "CompilerRT: Normalize COMPILER_RT_DEFAULT_TARGET_TRIPLE (#88835)"

This reverts commit 16f1887.

This broke Libcxx Picolib testing at the install step, and builds
for Windows builtins. Revert while we figure out the cause.

Author: DavidSpickett

compiler-rt/cmake/Modules/CompilerRTUtils.cmake

@@ -368,12 +368,6 @@ macro(construct_compiler_rt_default_triple)
           "Default triple for which compiler-rt runtimes will be built.")
   endif()
 
-  if ("${CMAKE_C_COMPILER_ID}" MATCHES "Clang")
-    execute_process(COMMAND ${CMAKE_C_COMPILER} --target=${COMPILER_RT_DEFAULT_TARGET_TRIPLE} -print-effective-triple
-                    OUTPUT_VARIABLE COMPILER_RT_DEFAULT_TARGET_TRIPLE
-                    OUTPUT_STRIP_TRAILING_WHITESPACE)
-  endif()
-
   string(REPLACE "-" ";" LLVM_TARGET_TRIPLE_LIST ${COMPILER_RT_DEFAULT_TARGET_TRIPLE})
   list(GET LLVM_TARGET_TRIPLE_LIST 0 COMPILER_RT_DEFAULT_TARGET_ARCH)