post, memory test: add memory_post_test() to include file

This include is needed, if this memory test is used "outside"
from post code, for example booting with nand_spl, and using
this memory test before copying u-boot code to RAM and jumping
to it.

Signed-off-by: Heiko Schocher <hs@denx.de>

include/post.h

@@ -187,6 +187,7 @@ extern int post_hotkeys_pressed(void);
 #define CONFIG_SYS_POST_CODEC		0x00200000
 #define CONFIG_SYS_POST_COPROC		0x00400000
 
+int memory_post_test(int flags);
 #endif /* CONFIG_POST */
 
 #endif /* _POST_H */