egl: fix function prototype for eglGetPlatformDisplay

The EGL 1.5 specification says that eglGetPlatformDisplay (unlike
eglGetPlatformDisplayExt) takes an EGLAttrib* rather than EGLint* for
the attribute list.

src/video/SDL_egl_c.h

@@ -46,7 +46,7 @@ typedef struct SDL_EGL_VideoData
     EGLDisplay(EGLAPIENTRY *eglGetDisplay) (NativeDisplayType display);
     EGLDisplay(EGLAPIENTRY *eglGetPlatformDisplay) (EGLenum platform,
                                 void *native_display,
-                                const EGLint *attrib_list);
+                                const EGLAttrib *attrib_list);
     EGLDisplay(EGLAPIENTRY *eglGetPlatformDisplayEXT) (EGLenum platform,
                                 void *native_display,
                                 const EGLint *attrib_list);