Fix {$LINKLIB} directives in SDL3_image

The {$LINKLIB} directives in SDL3_image.pas were instructing the
compiler to link against the base SDL3 library, instead of SDL3_image.

Author: suve

units/SDL3_image.pas

@@ -63,7 +63,7 @@ interface
     {$IFDEF DARWIN}
       IMG_LibName = 'libSDL3_image.dylib';
       {$IFDEF FPC}
-        {$LINKLIB libSDL3}
+        {$LINKLIB libSDL3_image}
       {$ENDIF}
     {$ELSE}
       {$IFDEF FPC}
@@ -77,7 +77,7 @@ interface
   {$IFDEF MACOS}
     IMG_LibName = 'SDL3_image';
     {$IFDEF FPC}
-      {$linklib libSDL3}
+      {$linklib libSDL3_image}
     {$ENDIF}
   {$ENDIF}