Add GIT version information (commid ID) to untagged U-Boot versions

As done in the linux kernel, the U-Boot version (U_BOOT_VERSION)
of all unreleased (untagged) U-Boot images will be automatically
extended upon compiletime with a part of the GIT commit ID and
possibly with "dirty" if uncommited changes are detected.

Here an example for the resulting version:
"U-Boot 1.1.4-g3457ac18-dirty"

The version is now maintained in the toplevel Makefile and the
version headers are autogenerated.

Patch by Stefan Roese, 9 Feb 2006
diff --git a/include/version.h b/include/version.h
index 4f8b498..b56d2e9 100644
--- a/include/version.h
+++ b/include/version.h
@@ -1,5 +1,5 @@
 /*
- * (C) Copyright 2000-2003
+ * (C) Copyright 2000-2006
  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
  *
  * See file CREDITS for list of people who contributed to this
@@ -24,6 +24,6 @@
 #ifndef	__VERSION_H__
 #define	__VERSION_H__
 
-#define	U_BOOT_VERSION	"U-Boot 1.1.4"
+#include "version_autogenerated.h"
 
 #endif	/* __VERSION_H__ */