Assorted portability enhancements (#1800)

* Introduce some Platform calls for managing dynamic libraries

* Add Platform::WriteFATSectors

* Introduce some Platform calls for managing dynamic libraries

* Add Platform::WriteFATSectors

* Change includes of "../types.h" to "types.h"

- Makes it easier to directly include these headers in downstream projects

* Change an include of "../Wifi.h" to "Wifi.h"

* Allow CommonFuncs.cpp to compile on Android

* Tidy up some logging calls

- Use Platform::Log in LAN_Socket.cpp
- Soften some warnings to Debug logs (since they don't necessarily represent problems)

* Add Platform::EnterGBAMode

- Gracefully stop the emulator if trying to enter GBA mode

* Soften some logs that most players won't care about

* Soften some more logs

* Introduce Platform wrappers for file operations

* Fix pointer spacing

* Fix more style nits

* Log the errno when ftruncate fails

* Fix FileSeek offset argument

- With an s32 offset, we couldn't access files larger than 2GB

* Revise Platform::StopEmu to address feedback

- Remove Platform::EnterGBAMode in favor of adding a reason to Platform::StopEmu
- Also rename Platform::StopEmu to Platform::SignalStop
- Add an optional argument to NDS::Stop
- Use the new argument everywhere that the console stops itself

* Rename FileGetString to FileReadLine

- It conveys the meaning better

* Rename FileSeekOrigin::Set to Start

- It conveys the meaning better

* Change definition of FileGetString to FileReadLine

- Oops, almost forgot it

* Rename FlushFile to FileFlush

- To remain consistent with the other File functions

* Add a FileType usage

* Fix line break in FileSeekOrigin

* Document Platform::DeInit

* Clarify that StopReason::Unknown doesn't always mean an error

* Move and document FileType::HostFile

* Remove Platform::OpenDataFile

- Nothing currently uses it

* Refactor Platform::OpenFile and Platform::OpenLocalFile to accept a FileMode enum instead of a string

- The enum is converted to fopen flags under the hood
- The file type is used to decide whether to add the "b" flag
- Some helper functions are exposed for the benefit of consistent behavior among frontends
- Equivalent behavior is maintained

* Fix a tab that should be spaces

* Use Windows' 64-bit implementations of fseek/ftell

* Move Platform::IsBinaryFile to Platform.cpp

- It could vary by frontend

* Remove an unused FileType

* Rename an enum constant

* Document various Platform items

* Use Platform::DynamicLibrary to load libandroid

- And clean it up at the end

* Fix a typo

* Pass the correct filetype to FATStorage

- Since it can be used for DSI NAND images or for SD cards

* Remove Platform::FileType

src/frontend/qt_sdl/LAN_PCap.cpp

@@ -21,9 +21,8 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <SDL2/SDL.h>
 #include <pcap/pcap.h>
-#include "../Wifi.h"
+#include "Wifi.h"
 #include "LAN_PCap.h"
 #include "Config.h"
 #include "Platform.h"
@@ -88,7 +87,7 @@ const char* PCapLibNames[] =
 AdapterData* Adapters = NULL;
 int NumAdapters = 0;
 
-void* PCapLib = NULL;
+Platform::DynamicLibrary* PCapLib = NULL;
 pcap_t* PCapAdapter = NULL;
 AdapterData* PCapAdapterData;
 
@@ -98,10 +97,10 @@ volatile int RXNum;
 
 
 #define LOAD_PCAP_FUNC(sym) \
-    ptr_##sym = (type_##sym)SDL_LoadFunction(lib, #sym); \
+    ptr_##sym = (type_##sym)DynamicLibrary_LoadFunction(lib, #sym); \
     if (!ptr_##sym) return false;
 
-bool TryLoadPCap(void* lib)
+bool TryLoadPCap(Platform::DynamicLibrary *lib)
 {
     LOAD_PCAP_FUNC(pcap_findalldevs)
     LOAD_PCAP_FUNC(pcap_freealldevs)
@@ -130,12 +129,12 @@ bool Init(bool open_adapter)
 
         for (int i = 0; PCapLibNames[i]; i++)
         {
-            void* lib = SDL_LoadObject(PCapLibNames[i]);
+            Platform::DynamicLibrary* lib = Platform::DynamicLibrary_Load(PCapLibNames[i]);
             if (!lib) continue;
 
             if (!TryLoadPCap(lib))
             {
-                SDL_UnloadObject(lib);
+                Platform::DynamicLibrary_Unload(lib);
                 continue;
             }
 
@@ -355,7 +354,7 @@ void DeInit()
             PCapAdapter = NULL;
         }
 
-        SDL_UnloadObject(PCapLib);
+        Platform::DynamicLibrary_Unload(PCapLib);
         PCapLib = NULL;
     }
 }