Fix -Wundef warnings due to use of unguarded __WINRT__

src/file/SDL_rwops.c

@@ -572,7 +572,7 @@ SDL_RWFromFile(const char *file, const char *mode)
     {
 #if defined(__APPLE__) && !SDL_FILE_DISABLED // TODO: add dummy?
         FILE *fp = SDL_OpenFPFromBundleOrFallback(file, mode);
-#elif __WINRT__
+#elif defined(__WINRT__)
         FILE *fp = NULL;
         fopen_s(&fp, file, mode);
 #elif defined(__3DS__)

src/render/opengles2/SDL_render_gles2.c

@@ -2135,7 +2135,7 @@ static SDL_Renderer *GLES2_CreateRenderer(SDL_Window *window, Uint32 flags)
         goto error;
     }
 
-#if __WINRT__
+#ifdef __WINRT__
     /* DLudwig, 2013-11-29: ANGLE for WinRT doesn't seem to work unless VSync
      * is turned on.  Not doing so will freeze the screen's contents to that
      * of the first drawn frame.

src/thread/windows/SDL_syscond_cv.c

@@ -56,7 +56,7 @@ typedef struct CONDITION_VARIABLE
 } CONDITION_VARIABLE, *PCONDITION_VARIABLE;
 #endif
 
-#if __WINRT__
+#ifdef __WINRT__
 #define pWakeConditionVariable     WakeConditionVariable
 #define pWakeAllConditionVariable  WakeAllConditionVariable
 #define pSleepConditionVariableSRW SleepConditionVariableSRW
@@ -224,7 +224,7 @@ SDL_CreateCond(void)
             SDL_assert(SDL_mutex_impl_active.Type != SDL_MUTEX_INVALID);
         }
 
-#if __WINRT__
+#ifdef __WINRT__
         /* Link statically on this platform */
         impl = &SDL_cond_impl_cv;
 #else

src/thread/windows/SDL_sysmutex.c

@@ -39,7 +39,7 @@ SDL_mutex_impl_t SDL_mutex_impl_active = { 0 };
  * Implementation based on Slim Reader/Writer (SRW) Locks for Win 7 and newer.
  */
 
-#if __WINRT__
+#ifdef __WINRT__
 /* Functions are guaranteed to be available */
 #define pReleaseSRWLockExclusive    ReleaseSRWLockExclusive
 #define pAcquireSRWLockExclusive    AcquireSRWLockExclusive
@@ -153,7 +153,7 @@ static SDL_mutex *SDL_CreateMutex_cs(void)
     if (mutex != NULL) {
         /* Initialize */
         /* On SMP systems, a non-zero spin count generally helps performance */
-#if __WINRT__
+#ifdef __WINRT__
         InitializeCriticalSectionEx(&mutex->cs, 2000, 0);
 #else
         InitializeCriticalSectionAndSpinCount(&mutex->cs, 2000);
@@ -224,7 +224,7 @@ SDL_CreateMutex(void)
         const SDL_mutex_impl_t *impl = &SDL_mutex_impl_cs;
 
         if (!SDL_GetHintBoolean(SDL_HINT_WINDOWS_FORCE_MUTEX_CRITICAL_SECTIONS, SDL_FALSE)) {
-#if __WINRT__
+#ifdef __WINRT__
             /* Link statically on this platform */
             impl = &SDL_mutex_impl_srw;
 #else

src/thread/windows/SDL_syssem.c

@@ -67,7 +67,7 @@ static SDL_sem_impl_t SDL_sem_impl_active = { 0 };
 #endif
 
 #if !SDL_WINAPI_FAMILY_PHONE
-#if __WINRT__
+#ifdef __WINRT__
 /* Functions are guaranteed to be available */
 #define pWaitOnAddress       WaitOnAddress
 #define pWakeByAddressSingle WakeByAddressSingle
@@ -232,7 +232,7 @@ static SDL_sem *SDL_CreateSemaphore_kern(Uint32 initial_value)
     sem = (SDL_sem_kern *)SDL_malloc(sizeof(*sem));
     if (sem != NULL) {
         /* Create the semaphore, with max value 32K */
-#if __WINRT__
+#ifdef __WINRT__
         sem->id = CreateSemaphoreEx(NULL, initial_value, 32 * 1024, NULL, 0, SEMAPHORE_ALL_ACCESS);
 #else
         sem->id = CreateSemaphore(NULL, initial_value, 32 * 1024, NULL);
@@ -343,7 +343,7 @@ SDL_CreateSemaphore(Uint32 initial_value)
 
 #if !SDL_WINAPI_FAMILY_PHONE
         if (!SDL_GetHintBoolean(SDL_HINT_WINDOWS_FORCE_SEMAPHORE_KERNEL, SDL_FALSE)) {
-#if __WINRT__
+#ifdef __WINRT__
             /* Link statically on this platform */
             impl = &SDL_sem_impl_atom;
 #else

src/video/SDL_video.c

@@ -1371,7 +1371,7 @@ static void SDL_CheckWindowDisplayChanged(SDL_Window *window)
     }
 }
 
-#if __WINRT__
+#ifdef __WINRT__
 extern Uint32 WINRT_DetectWindowFlags(SDL_Window *window);
 #endif
 
@@ -1467,7 +1467,7 @@ static int SDL_UpdateFullscreenMode(SDL_Window *window, SDL_bool fullscreen)
             goto done;
         }
     }
-#elif __WINRT__ && (NTDDI_VERSION < NTDDI_WIN10)
+#elif defined(__WINRT__) && (NTDDI_VERSION < NTDDI_WIN10)
     /* HACK: WinRT 8.x apps can't choose whether or not they are fullscreen
        or not.  The user can choose this, via OS-provided UI, but this can't
        be set programmatically.
@@ -1907,7 +1907,7 @@ SDL_Window *SDL_CreateWindowInternal(const char *title, int x, int y, int w, int
     }
 #endif
 
-#if __WINRT__ && (NTDDI_VERSION < NTDDI_WIN10)
+#if defined(__WINRT__) && (NTDDI_VERSION < NTDDI_WIN10)
     /* HACK: WinRT 8.x apps can't choose whether or not they are fullscreen
        or not.  The user can choose this, via OS-provided UI, but this can't
        be set programmatically.