uml: memcpy export needs to follow host declaration

x86_64 defines either memcpy or __memcpy depending on the gcc version, and
it looks like UML needs to follow that in its exporting.

Cc: Gabriel C <nix.or.die@googlemail.com>
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/um/sys-x86_64/ksyms.c

@@ -3,5 +3,9 @@
 #include <asm/checksum.h>
 
 /*XXX: we need them because they would be exported by x86_64 */
+#if (__GNUC__ == 4 && __GNUC_MINOR__ >= 3) || __GNUC__ > 4
+EXPORT_SYMBOL(memcpy);
+#else
 EXPORT_SYMBOL(__memcpy);
+#endif
 EXPORT_SYMBOL(csum_partial);