[llvm] [NFC][llvm-exegesis] Disable CFI-icall for JIT-executed function (PR #202472)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

This change also breaks compiling with MSVC:
```
llvm-project/llvm/tools/llvm-exegesis/lib/Assembler.h(118): error C3646: '__attribute__': unknown override specifier
llvm-project/llvm/tools/llvm-exegesis/lib/Assembler.h(117): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
llvm-project/llvm/tools/llvm-exegesis/lib/Assembler.h(117): error C2059: syntax error: '('
llvm-project/llvm/tools/llvm-exegesis/lib/Assembler.h(118): error C2059: syntax error: '('
llvm-project/llvm/tools/llvm-exegesis/lib/Assembler.h(114): error C2065: 'FunctionBytes': undeclared identifier
```


https://github.com/llvm/llvm-project/pull/202472