Remove superfluous attribute_hidden from function

definition. I seems to produce spurious warning:
libc/inet/resolv.c:1549: warning: 'visibility' attribute ignored on non-class types
(seems like gcc bug)
and it is not really needed - attribute_hidden was already
specified in function _declaration_ so it is not necessary here.

No code changes (verified with objdump).

libc/inet/resolv.c

@@ -1545,7 +1545,7 @@ libc_hidden_def(gethostbyaddr)
 
 #ifdef L_read_etc_hosts_r
 
-FILE * attribute_hidden __open_etc_hosts(void)
+FILE * __open_etc_hosts(void)
 {
 	FILE * fp;
 	if ((fp = fopen("/etc/hosts", "r")) == NULL) {