[llvm] Create a CharSetConverter class with both iconv and icu support (PR #74516)

[via llvm-commits]

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@@ -258,6 +258,37 @@ if(LLVM_HAS_LOGF128)
   set(LLVM_HAS_LOGF128 "${HAS_LOGF128}")
 endif()
 
+# Check for ICU.
+if(LLVM_ENABLE_ICU)
+  set(LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES})
+  set(CMAKE_FIND_LIBRARY_SUFFIXES ".so")
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paperchalice wrote:

Windows provides import library icu.lib (the dll is in Windows/system32) which is different with standard icu distribution and FindICU.cmake doesn't support Windows bundled ICU, so we may need some extra works here.

https://github.com/llvm/llvm-project/pull/74516