shared.c: return original errno

Noticed-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>
diff --git a/shared.c b/shared.c
index a27ab30..9362d21 100644
--- a/shared.c
+++ b/shared.c
@@ -400,15 +400,16 @@
  */
 int readfile(const char *path, char **buf, size_t *size)
 {
-	int fd;
+	int fd, e;
 	struct stat st;
 
 	fd = open(path, O_RDONLY);
 	if (fd == -1)
 		return errno;
 	if (fstat(fd, &st)) {
+		e = errno;
 		close(fd);
-		return errno;
+		return e;
 	}
 	if (!S_ISREG(st.st_mode)) {
 		close(fd);
@@ -416,7 +417,8 @@
 	}
 	*buf = xmalloc(st.st_size + 1);
 	*size = read_in_full(fd, *buf, st.st_size);
+	e = errno;
 	(*buf)[*size] = '\0';
 	close(fd);
-	return (*size == st.st_size ? 0 : errno);
+	return (*size == st.st_size ? 0 : e);
 }