[IR] Fixed ambiguous call to llvm::report_fatal_error

This patch fixes the following error with MSVC 16.9.2:
llvm/lib/IR/GCStrategy.cpp(35): error C2668: 'llvm::report_fatal_error': ambiguous call to overloaded function
llvm/include/llvm/Support/ErrorHandling.h(75): note: could be 'void llvm::report_fatal_error(const llvm::Twine &,bool)'
llvm/include/llvm/Support/ErrorHandling.h(73): note: or 'void llvm::report_fatal_error(llvm::StringRef,bool)'
llvm/lib/IR/GCStrategy.cpp(35): note: while trying to match the argument list '(const std::string)'

Reviewed By: RKSimon, barannikov88

Differential Revision: https://reviews.llvm.org/D130407