cpuinfo: Added SDL_GetSystemPageSize.

Fixes #14201.

test/testplatform.c

@@ -412,6 +412,7 @@ static int TestCPUInfo(bool verbose)
         SDL_Log("LSX %s", SDL_HasLSX() ? "detected" : "not detected");
         SDL_Log("LASX %s", SDL_HasLASX() ? "detected" : "not detected");
         SDL_Log("System RAM %d MB", SDL_GetSystemRAM());
+        SDL_Log("System memory page size %d bytes", SDL_GetSystemPageSize());
     }
     return 0;
 }

test/testsymbols.c

@@ -1339,6 +1339,7 @@ const static struct {
     SDL_SYMBOL_ITEM(SDL_LoadPNG),
     SDL_SYMBOL_ITEM(SDL_SavePNG_IO),
     SDL_SYMBOL_ITEM(SDL_SavePNG),
+    SDL_SYMBOL_ITEM(SDL_GetSystemPageSize),
     /* extra symbols go here (don't modify this line) */
     { NULL, NULL }
 };