[RFC PATCH u-boot 10/12] string: make memcpy() visible to fix LTO linking errors

["Marek Behún" <marek.behun@nic.cz>]

It seems that sometimes (happening on ARM64, for example with
turris_mox_defconfig) GCC, when linking with LTO, changes the name of
lib/string.c's memcpy() function to memcpy.isra.0.

This is a problem however when GCC for a code such as this:
	struct some_struct *info = get_some_struct();
	struct some struct tmpinfo;
	tmpinfo = *info;
emits a call to memcpy() by builtin behaviour, to copy *info to tmpinfo.

This then results in the following linking error:
  .../lz4.c:93: undefined reference to `memcpy'
  .../uuid.c:206: more undefined references to `memcpy' follow

Make memcpy() visible by using the __visible macro to avoid this error.

Signed-off-by: Marek Beh?n <marek.behun@nic.cz>
---
 lib/string.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/string.c b/lib/string.c
index 73b984123d..2290af83c4 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -16,6 +16,7 @@
  */
 
 #include <config.h>
+#include <linux/compiler.h>
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/ctype.h>
@@ -529,7 +530,7 @@ void * memset(void * s,int c,size_t count)
  * You should not use this function to access IO space, use memcpy_toio()
  * or memcpy_fromio() instead.
  */
-void * memcpy(void *dest, const void *src, size_t count)
+__visible void * memcpy(void *dest, const void *src, size_t count)
 {
 	unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
 	char *d8, *s8;
-- 
2.26.2