[ClangCL] exception related fix for ClangCL (#5496)

Enable Exception for ClangCL.
Disable the DivByZero exception test for ClangCL.

This is for turn on ClangCL build.

cmake/modules/AddLLVM.cmake

@@ -9,7 +9,7 @@ function(llvm_update_compile_flags name)
 
   # LLVM_REQUIRES_EH is an internal flag that individual
   # targets can use to force EH
-  if((LLVM_REQUIRES_EH OR LLVM_ENABLE_EH) AND NOT CLANG_CL)
+  if(LLVM_REQUIRES_EH OR LLVM_ENABLE_EH) # HLSL Change - allow CLANG_CL to use EH.
     if(NOT (LLVM_REQUIRES_RTTI OR LLVM_ENABLE_RTTI))
       message(AUTHOR_WARNING "Exception handling requires RTTI. Enabling RTTI for ${name}")
       set(LLVM_REQUIRES_RTTI ON)

tools/clang/unittests/HLSL/CompilerTest.cpp

@@ -3764,7 +3764,8 @@ TEST_F(CompilerTest, CompileHlsl2022ThenFail) {
   CheckOperationResultMsgs(pResult, &pErrorMsg, 1, false, false);
 }
 
-#if defined(_WIN32) && !(defined(_M_ARM64) || defined(_M_ARM64EC)) // this test has issues on ARM64; disable until we figure out what it going on
+// this test has issues on ARM64 and clang_cl, disable until we figure out what it going on
+#if defined(_WIN32) && !(defined(_M_ARM64) || defined(_M_ARM64EC) || defined(__clang__))
 
 #pragma fenv_access(on)
 #pragma optimize("", off)