unify version_string

This patch removes the architecture specific implementation of
version_string where possible. Some architectures use a special place
and therefore we provide U_BOOT_VERSION_STRING definition and a common
weak symbol version_string.

Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
CC: Mike Frysinger <vapier@gentoo.org>
CC: Peter Pan <pppeterpppan@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/common/cmd_version.c b/common/cmd_version.c
index 83cb11c..e4b2ac1 100644
--- a/common/cmd_version.c
+++ b/common/cmd_version.c
@@ -24,8 +24,9 @@
 #include <common.h>
 #include <command.h>
 #include <version.h>
+#include <linux/compiler.h>
 
-extern char version_string[];
+const char __weak version_string[] = U_BOOT_VERSION_STRING;
 
 int do_version(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
diff --git a/common/main.c b/common/main.c
index 1f22142..3324d9d 100644
--- a/common/main.c
+++ b/common/main.c
@@ -30,6 +30,7 @@
 #include <common.h>
 #include <watchdog.h>
 #include <command.h>
+#include <version.h>
 #ifdef CONFIG_MODEM_SUPPORT
 #include <malloc.h>		/* for free() prototype */
 #endif
@@ -307,8 +308,6 @@
 
 #ifdef CONFIG_VERSION_VARIABLE
 	{
-		extern char version_string[];
-
 		setenv ("ver", version_string);  /* set version variable */
 	}
 #endif /* CONFIG_VERSION_VARIABLE */