InternalizePass should consider built-in functions.

[DianQK]

We should preserve built-in functions when running InternalizePass.

Similar to

llvm-project/llvm/lib/Transforms/IPO/Internalize.cpp

Lines 230 to 234 in 39d8e6e

	AlwaysPreserved.insert("__stack_chk_fail");
	if (Triple(M.getTargetTriple()).isOSAIX())
	AlwaysPreserved.insert("__ssp_canary_word");
	else
	AlwaysPreserved.insert("__stack_chk_guard");

and

llvm-project/llvm/lib/Object/IRSymtab.cpp

Lines 48 to 57 in 7021182

	static const char *PreservedSymbols[] = {
	#define HANDLE_LIBCALL(code, name) name,
	#include "llvm/IR/RuntimeLibcalls.def"
	#undef HANDLE_LIBCALL
	// There are global variables, so put it here instead of in
	// RuntimeLibcalls.def.
	// TODO: Are there similar such variables?
	"__ssp_canary_word",
	"__stack_chk_guard",
	};

.

Related issue: rust-lang/rust#113923.

[DianQK]

We can choose to have the compiler collect these symbols.