use memset macros instead of fn in x11 demos

demo/x11/nuklear_xlib.h

@@ -863,7 +863,7 @@ nk_xlib_shutdown(void)
     nk_xsurf_del(xlib.surf);
     nk_free(&xlib.ctx);
     XFreeCursor(xlib.dpy, xlib.cursor);
-    nk_memset(&xlib, 0, sizeof(xlib));
+    NK_MEMSET(&xlib, 0, sizeof(xlib));
 }
 
 NK_API void

demo/x11_rawfb/nuklear_rawfb.h

@@ -821,7 +821,7 @@ nk_rawfb_init(void *fb, void *tex_mem, const unsigned int w, const unsigned int
     if (!rawfb)
         return NULL;
 
-    nk_memset(rawfb, 0, sizeof(struct rawfb_context));
+    NK_MEMSET(rawfb, 0, sizeof(struct rawfb_context));
     rawfb->font_tex.pixels = tex_mem;
     rawfb->font_tex.format = NK_FONT_ATLAS_ALPHA8;
     rawfb->font_tex.w = rawfb->font_tex.h = 0;
@@ -1015,7 +1015,7 @@ nk_rawfb_shutdown(struct rawfb_context *rawfb)
 {
     if (rawfb) {
 	nk_free(&rawfb->ctx);
-	nk_memset(rawfb, 0, sizeof(struct rawfb_context));
+	NK_MEMSET(rawfb, 0, sizeof(struct rawfb_context));
 	free(rawfb);
     }
 }

demo/x11_rawfb/nuklear_xlib.h

@@ -286,7 +286,7 @@ nk_xlib_shutdown(void)
         XDestroyImage(xlib.ximg);
         shmdt(xlib.xsi.shmaddr);
         shmctl(xlib.xsi.shmid, IPC_RMID, NULL);
-    } nk_memset(&xlib, 0, sizeof(xlib));
+    } NK_MEMSET(&xlib, 0, sizeof(xlib));
 }
 
 NK_API void

demo/x11_xft/nuklear_xlib.h

@@ -941,7 +941,7 @@ nk_xlib_shutdown(void)
     nk_xsurf_del(xlib.surf);
     nk_free(&xlib.ctx);
     XFreeCursor(xlib.dpy, xlib.cursor);
-    nk_memset(&xlib, 0, sizeof(xlib));
+    NK_MEMSET(&xlib, 0, sizeof(xlib));
 }
 
 NK_API void