Windows: Try to use xinput9_1_0.dll if XInput 1.4 and 1.3 are not available.

XInput "9.1.0" ships with Windows Vista and 7 systems, but it lacks some features, including support for detecting Guide button presses.

src/core/windows/SDL_xinput.c

@@ -84,11 +84,15 @@ WIN_LoadXInputDLL(void)
     s_pXInputDLL = LoadLibrary(L"XInput1_4.dll");  /* 1.4 Ships with Windows 8. */
     if (!s_pXInputDLL) {
         version = (1 << 16) | 3;
-        s_pXInputDLL = LoadLibrary(L"XInput1_3.dll");  /* 1.3 Ships with Vista and Win7, can be installed as a redistributable component. */
+        s_pXInputDLL = LoadLibrary(L"XInput1_3.dll");  /* 1.3 can be installed as a redistributable component. */
     }
     if (!s_pXInputDLL) {
         s_pXInputDLL = LoadLibrary(L"bin\\XInput1_3.dll");
     }
+    if (!s_pXInputDLL) {
+        /* "9.1.0" Ships with Vista and Win7, and is more limited than 1.3+ (e.g. XInputGetStateEx is not available.)  */
+        s_pXInputDLL = LoadLibrary(L"XInput9_1_0.dll");
+    }
     if (!s_pXInputDLL) {
         return -1;
     }
@@ -99,6 +103,9 @@ WIN_LoadXInputDLL(void)
 
     /* 100 is the ordinal for _XInputGetStateEx, which returns the same struct as XinputGetState, but with extra data in wButtons for the guide button, we think... */
     SDL_XInputGetState = (XInputGetState_t)GetProcAddress((HMODULE)s_pXInputDLL, (LPCSTR)100);
+    if (!SDL_XInputGetState) {
+        SDL_XInputGetState = (XInputGetState_t)GetProcAddress((HMODULE)s_pXInputDLL, "XInputGetState");
+    }
     SDL_XInputSetState = (XInputSetState_t)GetProcAddress((HMODULE)s_pXInputDLL, "XInputSetState");
     SDL_XInputGetCapabilities = (XInputGetCapabilities_t)GetProcAddress((HMODULE)s_pXInputDLL, "XInputGetCapabilities");
     if (!SDL_XInputGetState || !SDL_XInputSetState || !SDL_XInputGetCapabilities) {