Move DECLARE_GLOBAL_DATA_PTR to file scope

It can be optimised out by the compiler otherwise resulting
in obscure errors like a board not booting.

This has been documented in README since 2006 when these were
first fixed up for GCC 4.x.

Signed-off-by: John Rigby <john.rigby@linaro.org>

Fix some additional places.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Acked-By: Albert ARIBAUD <albert.aribaud@free.fr>
diff --git a/arch/blackfin/cpu/serial.c b/arch/blackfin/cpu/serial.c
index 901cb97..650202e 100644
--- a/arch/blackfin/cpu/serial.c
+++ b/arch/blackfin/cpu/serial.c
@@ -42,6 +42,8 @@
 #include <asm/blackfin.h>
 #include <asm/mach-common/bits/uart.h>
 
+DECLARE_GLOBAL_DATA_PTR;
+
 #ifdef CONFIG_UART_CONSOLE
 
 #include "serial.h"
@@ -95,7 +97,6 @@
  */
 void serial_setbrg(void)
 {
-	DECLARE_GLOBAL_DATA_PTR;
 	serial_set_baud(gd->baudrate);
 }