Modifying expression code in MakeLoadImageUtilityFunction to be more consistent

[shafik]

Summary

MakeLoadImageUtilityFunction() is not using extern "C" for external C functions and it is not using eLanguageTypeC_plus_plus. So I am modifying it to be consistent.

[shafik]

Note, we have a few tests that cover LoadImage:

TestCompletion.py
TestLoadUsingLazyBind.py
TestLoadUsingPaths.py

So they should be covering this code.

[JDevlieghere]

We do the same thing for parsing the classes from the Objective-C runtime so this makes sense to me. LGTM.

[aprantl]

Did you check if we have other helper expressions with the same problem?

[shafik]

In D121831#3390152, @aprantl wrote:

Did you check if we have other helper expressions with the same problem?

Yes, I could not find any other instances like this. They are not straight forward to find but I think I found all the places this could matter.

lldb/source/Plugins/Platform/POSIX/PlatformPOSIX.cpp

PlatformPOSIX::MakeLoadImageUtilityFunction(ExecutionContext &exe_ctx,
   static const char *dlopen_wrapper_code = R"(
   const int RTLD_LAZY = 1;
 
   struct __lldb_dlopen_result {
     void *image_ptr;
     const char *error_str;
   };
   
-  extern void *memcpy(void *, const void *, size_t size);
-  extern size_t strlen(const char *);
+  extern "C" void *memcpy(void *, const void *, size_t size);
+  extern "C" size_t strlen(const char *);
   
 
   void * __lldb_dlopen_wrapper (const char *name, 
                                 const char *path_strings,
                                 char *buffer,
                                 __lldb_dlopen_result *result_ptr)
   {
     // This is the case where the name is the full path:
PlatformPOSIX::MakeLoadImageUtilityFunction(ExecutionContext &exe_ctx,
   Process *process = exe_ctx.GetProcessSP().get();
   // Insert the dlopen shim defines into our generic expression:
   std::string expr(std::string(GetLibdlFunctionDeclarations(process)));
   expr.append(dlopen_wrapper_code);
   Status utility_error;
   DiagnosticManager diagnostics;
 
   auto utility_fn_or_error = process->GetTarget().CreateUtilityFunction(
-      std::move(expr), dlopen_wrapper_name, eLanguageTypeObjC, exe_ctx);
+      std::move(expr), dlopen_wrapper_name, eLanguageTypeC_plus_plus, exe_ctx);
   if (!utility_fn_or_error) {
     std::string error_str = llvm::toString(utility_fn_or_error.takeError());
     error.SetErrorStringWithFormat("dlopen error: could not create utility"
                                    "function: %s",
                                    error_str.c_str());
     return nullptr;
   }
   std::unique_ptr<UtilityFunction> dlopen_utility_func_up =