Re-added SDL_SoftStretch() to the API

This is needed for sdl2-compat, since a blit is not quite equivalent.

src/dynapi/SDL_dynapi.sym

@@ -1233,6 +1233,7 @@ SDL3_0.0.0 {
     SDL_AudioStreamDevicePaused;
     SDL_ClickTrayEntry;
     SDL_UpdateTrays;
+    SDL_SoftStretch;
     # extra symbols go here (don't modify this line)
   local: *;
 };

src/dynapi/SDL_dynapi_overrides.h

@@ -1258,3 +1258,4 @@
 #define SDL_AudioStreamDevicePaused SDL_AudioStreamDevicePaused_REAL
 #define SDL_ClickTrayEntry SDL_ClickTrayEntry_REAL
 #define SDL_UpdateTrays SDL_UpdateTrays_REAL
+#define SDL_SoftStretch SDL_SoftStretch_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -1266,3 +1266,4 @@ SDL_DYNAPI_PROC(SDL_ThreadState,SDL_GetThreadState,(SDL_Thread *a),(a),return)
 SDL_DYNAPI_PROC(bool,SDL_AudioStreamDevicePaused,(SDL_AudioStream *a),(a),return)
 SDL_DYNAPI_PROC(void,SDL_ClickTrayEntry,(SDL_TrayEntry *a),(a),)
 SDL_DYNAPI_PROC(void,SDL_UpdateTrays,(void),(),)
+SDL_DYNAPI_PROC(bool,SDL_SoftStretch,(SDL_Surface *a,const SDL_Rect *b,SDL_Surface *c,const SDL_Rect *d,SDL_ScaleMode e),(a,b,c,d,e),return)