[LLDB] Modifying expression code in MakeLoadImageUtilityFunction to be more consistent

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.

Also see: rdar://87544782

Differential Revision: https://reviews.llvm.org/D121831

(cherry picked from commit 33d7417)

Author: shafik

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

@@ -576,8 +576,8 @@ PlatformPOSIX::MakeLoadImageUtilityFunction(ExecutionContext &exe_ctx,
     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, 
@@ -624,7 +624,7 @@ PlatformPOSIX::MakeLoadImageUtilityFunction(ExecutionContext &exe_ctx,
   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"