um: Add include: memset() and memcpy() are in <string.h>

These two functions are otherwise unknown to the pedantic compiler.
Include the correct header to enable the build to succeed.

Signed-off-by: Zach van Rijn <[email protected]>
Acked-By: Anton Ivanov <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>

Author: zv-io

arch/um/os-Linux/file.c

@@ -6,6 +6,7 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <string.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>