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

[Abhina Sree via llvm-commits]

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@@ -294,6 +294,37 @@ if(LLVM_HAS_LOGF128)
   set(LLVM_HAS_LOGF128 "${HAS_LOGF128}")
 endif()
 
+# Check for ICU.
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abhina-sree wrote:

I've added an extra comment for this here, thanks!

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