PluginManager: Don't cast from void-pointer to pointer-to-function

[majnemer]

Summary

GCC warns on reinterpret_cast expressions involving a void-pointer
source and a pointer-to-function destination. Take a detour through
intptr_t to silence it.

[majnemer]

Closed by commit rL213691 (authored by @majnemer).

lldb/trunk/source/Core/PluginManager.cpp

 SetPluginInfo (const FileSpec &plugin_file_spec, const PluginInfo &plugin_info)
 {
     Mutex::Locker locker (GetPluginMapMutex ());
     PluginTerminateMap &plugin_map = GetPluginMap ();
     assert (plugin_map.find (plugin_file_spec) == plugin_map.end());
     plugin_map[plugin_file_spec] = plugin_info;
 }
 
+template <typename FPtrTy>
+static FPtrTy
+CastToFPtr (void *VPtr)
+{
+    return reinterpret_cast<FPtrTy>(reinterpret_cast<intptr_t>(VPtr));
+}
 
 static FileSpec::EnumerateDirectoryResult 
 LoadPluginCallback 
 (
     void *baton,
     FileSpec::FileType file_type,
     const FileSpec &file_spec
 )
if (file_type == FileSpec::eFileTypeRegular         ||
             uint32_t flags = Host::eDynamicLibraryOpenOptionLazy |
                              Host::eDynamicLibraryOpenOptionLocal |
                              Host::eDynamicLibraryOpenOptionLimitGetSymbol;
 
             plugin_info.plugin_handle = Host::DynamicLibraryOpen (plugin_file_spec, flags, error);
             if (plugin_info.plugin_handle)
             {
                 bool success = false;
-                plugin_info.plugin_init_callback = (PluginInitCallback)Host::DynamicLibraryGetSymbol (plugin_info.plugin_handle, "LLDBPluginInitialize", error);
+                plugin_info.plugin_init_callback =
+                    CastToFPtr<PluginInitCallback>(
+                        Host::DynamicLibraryGetSymbol(plugin_info.plugin_handle,
+                                                      "LLDBPluginInitialize",
+                                                      error));
                 if (plugin_info.plugin_init_callback)
                 {
                     // Call the plug-in "bool LLDBPluginInitialize(void)" function
                     success = plugin_info.plugin_init_callback();
                 }
 
                 if (success)
                 {
                     // It is ok for the "LLDBPluginTerminate" symbol to be NULL
-                    plugin_info.plugin_term_callback = (PluginTermCallback)Host::DynamicLibraryGetSymbol (plugin_info.plugin_handle, "LLDBPluginTerminate", error);
+                    plugin_info.plugin_term_callback =
+                        CastToFPtr<PluginTermCallback>(
+                            Host::DynamicLibraryGetSymbol(
+                                plugin_info.plugin_handle, "LLDBPluginTerminate",
+                                error));
                 }
                 else 
                 {
                     // The initialize function returned FALSE which means the
                     // plug-in might not be compatible, or might be too new or
                     // too old, or might not want to run on this machine.
                     Host::DynamicLibraryClose (plugin_info.plugin_handle);
                     plugin_info.plugin_handle = NULL;