libc: remove private declarations from <time.h> and <resolv.h>

This patch is used to remove private C library declarations from the
public headers (that are exported to the NDK). It should *only* be
submitted after all other patches modifying the users of said
private functions have been submitted to the tree, to avoid
breakages.

Change-Id: I0a5e3014f8e3ac9ed8df86a5cdae506337c23252

libc/tzcode/strftime.c

@@ -38,6 +38,7 @@ static const char   sccsid[] = "@(#)strftime.c  5.4 (Berkeley) 3/14/89";
 #include "locale.h"
 #include <ctype.h>
 #include <time64.h>
+#include <bionic_time.h>  /* for strftime_tz */
 
 /* struct lc_time_T is now defined as strftime_locale
  * in <time.h>