Fix the build with -fno-common

Index: wmgeneral.c
--- wmgeneral.c.orig
+++ wmgeneral.c
@@ -58,6 +58,11 @@
  /* X11 Variables */
 /*****************/
 
+Display *display;
+Window Root, iconwin, win;
+XpmIcon wmgen;
+XpmIcon wmfont;
+
 int screen;
 int x_fd;
 int d_depth;
