Make examples' shebang use target tcc bindir path

Use @BINDIR@ in shebang of examples to put the right path on the target
system. That is, use #!/usr/local/bin/tcc if tcc is installed in /usr/local/bin
and #!/usr/bin/tcc if tcc is installed in /usr/bin/tcc.

examples/ex4.c.template

@@ -0,0 +1,26 @@
+#! @BINDIR@/tcc -run -L/usr/X11R6/lib -lX11
+#include <stdlib.h>
+#include <stdio.h>
+#include <X11/Xlib.h>
+
+/* Yes, TCC can use X11 too ! */
+
+int main(int argc, char **argv)
+{
+    Display *display;
+    Screen *screen;
+
+    display = XOpenDisplay("");
+    if (!display) {
+        fprintf(stderr, "Could not open X11 display\n");
+        exit(1);
+    }
+    printf("X11 display opened.\n");
+    screen = XScreenOfDisplay(display, 0);
+    printf("width = %d\nheight = %d\ndepth = %d\n",
+           screen->width,
+           screen->height,
+           screen->root_depth);
+    XCloseDisplay(display);
+    return 0;
+}